SpybotSD.exe deletion

[alchemist]

In spite aof the presence of a antivirus software i was affected by one or plus malaware [ named pokapoka61 - mediaaccces - exefld ].
To clear my PC i try with SpyBot but the link is wrong by the absence of the file exe ( spybotSD.exe), so i copy this file on e USB key from an other PC.
When i connect the key to the port i can just see the file few second before an automatic deletion.
The same for the exe of many utility software eg. norton systemwork, client antivirus ecc.
If i set attribute, in USB key, is "read only" the file is not deleted, but is promptly deleted after copy on hard disk; other way there is an error message impossible to copy file.
Other syntoms : WinXP don't start on safe mode by pressing F8 and choosing safe mode there is a switch off and restaring.
Regedit and other software for regestry cleaning don't work or cause a system restart.

Now mi PC is usable, quite good, but spybotSD dont'start because of the exe file absence.
Any lillte help from my fiends ?

Thank You very much

PS. I will send e segnalation to antivirus software house becouse i need more security on my PC.

[Tom.K]

If you want to remove a malware, first read this thread:
"BEFORE you POST"(READ this Procedure BEFORE Requesting Assistance) (http://forums.spybot.info/showthread.php?t=288)

Then create a thread in Malware Removal (http://forums.spybot.info/forumdisplay.php?f=22) forum.