Administrator account does not have permissions

I have been having this issue with my notebook. I can not access certain exe files from my desktop. There is only one account on this computer, it is mine, and it is the administrator.

I can click on the opera icon (not just opera but an example of the problem) on my desktop and get the message, "Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item."

If I go through the start menu I don't have any trouble accessing the same programs. I cannot download to my desktop because I won't be allowed to open those files either.

I read a forum where a guy said he had the same issue and it was a worm. I updated all my virus, spyware, and other malware program removers, scanned my computer, and removed everything that came up but that did not fix the problem. I even went and got a copy of norton antivirus just to cover all the bases and that did not help.

Dell Inspiron 6000
2Ghz 2Gb Ram

Thanks in advance for any help
A

 

Windows XP Media Center Edition.
Yes networked. I set up the network myself and included my desktop and a desktop at work to connect wirelessly. I am a novice at networking so if you think I might have messed something up while connecting the comps that could be feazable.

Thanks so much for your time!!