Hold F8 on start up to get to safe mode and if it wont load windows in safe mode and try a system restore point to a date before you killed it.

If it wont load windows from the F8 safe menu choose last known working configuration.

Just want to point out that each year, the subscription for "Nortons" has to be renewed. Some people dont realize that and figure if they bought a copy of Nortons in 2007 its still good.
I would seriously consider removing "Nortons" with their removal tool and installing a free Antivirus which is much better. Either Avast or Avira. Both of these are very good and most people will tell you they are better than"Nortons'.

Try system restore, then get rid of Norton, it's crap!! and takes over your PC, doesn't catch many viruses anyway, then download free AVG, and Free Malewarebytes, do a full scan with malewarebytes.

never never never fall for any of that stuff that guarantees it will remove stuff unless you come to a reputable forum and ask if the program is legit or a rogue! Keep a very close watch on your credit card if you used it to purchase anything. Spyware doctor is ok it is by pc tools but it is not what you need for the kind of infections you have. You most definitely need to use malwarebytes and superantispyware both free. But you have to get the pc to boot before you can do any of that. Let us know if you are able to use safe mode or last known good configuration.

How to download and install Malwarebytes' Anti-Malware application for Windows computers
SUPERAntiSpyware Free Edition

To remove Norton you will need the appropriate removal tool
Antivirus Product Removal Tools

avast! antivirus Home Edition

there are the links for what you will need if you can get it up.
and with the kind of infection you are talking about you will need to go to another pro support forum to run additional scans and guided programs.
Analysis and Malware Removal

My son's pc had a nasty virus that wouldn't go away but I managed to follow a thread that dealt with my exact problem at the malwarebytes forum. It took some time on my part to actually go through with it but I printed out the forum thread, read it over again and again and somehow rounded up the courage to tackle it a few days later (the instructions were 5 pages long!). His computer had some kind of trojan in the memory boot sector and while that may not be your problem, the point to remember is that somewhere, someone has gone through what you are now and you should not blame yourself for trying to help. Keep searching and do the best you can, that's all anyone can ask of you anyway. All the best.

P.S. Lessons learned: *His paid security program (antivirus, firewall and antispyware) was useless
*He was no longer permitted to run the computer in administrator mode. Windows updates can still be downloaded but on patch Tuesdays, I turn the computer on and log in as an administrator to make sure they can all install. (I believe some malware like the Zeus trojan can still surreptitiously install even in limited user mode)
*Malwarebytes and Avira rock!

Here is a link that might be useful: Malwarebytes forum

please please any time you have a problem start a new thread on any of the help forums asking for help for your problem, never follow the directions given on any of the support forums to someone else's problem. It must be specific to YOUR computer we can not stress that enough. Especially if combo fix is involved, these programs are to be used under the direct guidance of one of the support forum experts. following the directions specified for someone else with similar sounding issues can be harmful.
Start a thread of your own and explain your exact problem and get assistance dedicated to your pc and what is on your pc. They are always happy to help but all of the forums stress to start your own thread and only follow the directions given for your situation.
Following through with all the directions and having them check at the end to make sure all was taken care of is essential because many of those special programs need to be terminated and removed from the pc after use.

Following the general use directions for malwarebytes is fine, running the scans is advised.

Thanks everybody, I do renew my Norton every year, so no problem there.
We unpluged the PC for couple of minutes and after that it did turn on. I couldn't do anything before that b/c there was no power going in-have no idea why. So the thing is on and works even w/the virus on as long as we don't turn the computer off.
System restore is not restoring, even on my other computer-it stopped restoring looong time ago.I have no idea what to do w/that.The settings sems o.k. My BF has someone in the family who is able to fix it next week. I'm glad, I felt bad thinking I killed the thing.
I will not try do anything else, something like safe mode etc, scares me.
I tried Avast and could not get it for free, it asked for money.
I will check the malvarebytes forum too for future references. Thanks so much!!!!!

See Link

Here is a link that might be useful: FREE AVAST

if he goes to the link in my post that is labeled
Analysis and Malware removal, at LzD, they will assist him in removal, he will need this type of assistance or it will not be gone as you found out previously.
The infection will definitely prevent you from trying to install new programs that would try to remove it, that is a normal tactic for these infections, it will also render your current programs to not function properly so it is questionable whether or not your Norton is able to function as it should since the infection has likely altered it.
AVAST is free but you can NOT have 2 antivirus programs running on the pc at the same time so unless you have removed the Norton you do not want to install any other antivirus programs. The malwarebytes is ok to install and run and definitely should be run if the infection will allow it. The LzD link I provided can assist in getting the pc to allow the programs to be installed and run.

As shown on the siri.urz blog cyber security is one of the current known fake AV infections, it is not easy to eliminate and need the use of specialized programs and tools with analysis.
Cyber Security is a fake security application.

for an idea of just how many of these things are out there that we fight daily just scan through that blog!

Here is a link that might be useful: blog