Parallels Tools will not install

I am running Parallels Build 5608 on an iMac with a Windows XP guest operating system. Most things work fine, but I cannot install Parallels Tools. I am logged into XP as an administrator, and when I click on "Install Parallels Tools", the menu item changes to "Cancel Parallels Tools installation", but nothing happens... ever. The menu items will go back and forth, but the tools are not installed. I will greatly appreciate any help with this. Thank you.

 

I accidentally figured out what was wrong (I think). AVG Anti-virus had announced it couldn't run in my VM, which I assumed was because I hadn't copied all my data files. So I decided to uninstall it and reinstall it later. After I uninstalled AVG, I tried again to install Parallels Tools, and it worked. Heh.