Virus Problems

[cemucan]

Hi, my desktop seems to be inflected.
I cannot run windows safe mode,
I cannot install and run any antivirus/anti maleware program (including spybot)
I cannot run hijackthis
My computer cannot complete any online virus scan (eset, symantec, it does not connect to some web sites -kaspersky/housecall trend micro)
I cannot open task manager
I cannot use run/ regedit commands

Any suggestions would be highly appreciated
Regards,
cem

OS: Windows XP Home, intel 2.666hz CPU, w/1 gb ram.