Vista suddenly demands Admin rights for deleting/editing files/folders

Hey.
I noticed two-three days ago that Windows 7 suddenly started to demand admin rights to delete or edit some folders. It does not seem to be any specific folders, sometimes it works to delete and sometimes it does not. I tried to download some files to a folder a few minutes ago and most of the files were downloaded, but one of the files Vista starts to demand admin rights to write into the same folder that the other files were saved to. When I try again with the same file that failed it works without problem.

I have made some changes lately in MSConfig and turned off some services that should be "safe" to turn off according to several webguides. Maybe it has something to do with that? I am not sure which service could be the problem though.

I have been thinking it could be a virus maybe, since it does work sometimes and sometimes not.

Please note that I have had NO problems with the admin rights part so far until this started to happen. I am not sure if the changes started to happen before or after the changes in services startup.