Menu problem in XP

I am running Win XP Pro and recently I noticed that when I right click on a Drive or a folder in Windows Explorer, it takes about 5 minutes to get a menu. This does not happen if I pick a file inside a folder to right click on. It only happens with drives and folders. I have already tried running the latest service pack, defraging and running chkdisk. Nothing has changed. No new programs have been installed. I am running Symantec AV Corp. I have updated and ran a full scan for viruses. Nothing. Any ideas?