Worse than BSOD. Trojan or Virus. Urgent Help!!

Cause: Trojan or Virus. Unsure. Most likely contracted from an infected webpage/website.

I've never experienced anything like this before. There was no BSOD but this is so severe, I had to turn to the power off and am too scared to switch on computer.

Effect:
1. web browser (IE, version ?) couldn't function, except load homepage (which I have always set to Google). Error message:
Microsoft Visual C++ Runtime Library
Runtime error
C:\program files\internet explorer\IEXPLORER.EXE
R6025
-pure virtual function call

2.I tried to open Ewido. Error message:
Not enough quota is available to process this command.

3.Tried to open HijackThis but could not access hard-drive.Error message:
Not enough quota is available to process this command.

4.Tried again to open Ewido via shortcut. Error message:
This no longer exists. It might have been renamed, moved or deleted. Would you like to remove from list? (I pressed No)

5.Tried again to open Ewido. Error message:
Application failed to initialize properly (0xc000012d). Click to terminate application.

6.Tried to open Ewido again. Error message:
SecuritySuite.exe -Bad Image
The application or DLL C:\windows\system32\PSAPI.DLL is not a valid Windows image. Please check this against your installation diskette.

7.Opened Spybot, forced to download updates before scanning. Then couldn't find anything after scanning for only few seconds (unusual- scans always take over 5mins). Error message:
C:\windows\system32\SHDOCVW.DLL is not a windows image. Check this against your diskette.

8.Pressed scan button in Spybot to scan again but no response. Then when I tried to close it, Spybot started scanning (delayed response?). I kept trying to close Spybot because I thought it wouldn't work anyway. Then I tried to shut down computer but no response so I turned the power off. Computer is still off.

Thank you very much for reading this post. I'm sorry it was long, but since I don't know alot I put all the information I had. Help would be deeply appreciated.