"Cannot Install This Hardware" "Access is Denied"

I’ve a desktop running with ATI Radeon X300 display adapter. Due to some reason I need to update the drivers for the same but I can’t. I even tried editing the registry entry that enables registry updates to be logged but no help. When I checked C:\WINDOWS \setupapi.log which I setup for logging says “Error 5: Access is Denied.”

Is there any fix for the same?

Were you able to change the registry which you were trying? Am asking this because I strongly suspect there would be security/anti-malware software that is prevent all these action and hence you getting the error.

Thanks for your suggestion Janairo. I was not aware of this. Though earlier I tried disabling SpyBot (which obviously dint helped) but I forgot to disable my antivirus. Will do it in next few hours and let you know the results. Thanks again.