out of the blue, I can't install programs anymore under XP, SP2. Instead of starting the setup (on double-click) I am presented with a message that I "do not have sufficient rights to install the program". But I am the administrator and I am logged as admin.

I even can not copy files from one HDD to the other. Windows will tell me it can't copy the files, because they are unreadable...

So, I use copy command for the files and paste it to my flash memory stick. Surprise surprise. It works and I can install the program from the stick.

Any idea what has happend?

No, its not a virus or malware... that has been already checked

Thanks

Edited July 22, 200818 yr by webfact

Your files system rights are incorrect. You could try the following (not saying this will work). Use the explorer, right click the drive concerned, properties, and then security, see what NFTS right are set. usually the group administrators should have all rights, make sure your userprofile is member of that group, if it isn't, and it will not let you add it (most propably), go to advanced, and see if you can make that group (or your userprofile) owner of the files on the relevant tab. This might take a very long time, but it will properly set your file system rights again. I would advice you to use the administrators group. (and make your profile member of that group).

(don't forget to tick replace owner on subcontainters and objects).