Parallels 4 Drag and Drop Working Slowly

I am running identical versions of Parallels on two Macs.
Running Parallels 4.0.3846 with Mac OS 10.6.2 on Intel Core 2 Duo with Windows XP.

On the iMac, Parallels suddenly refused to do drag and drop from Mac to Windows. However, Parallels could do drag and drop from Windows to Mac.

I deleted and reinstalled Parallels Tools. No joy. I replaced the Win XP image with a known good backup. No joy. I manually removed all of Parallels 4, including the prefs files and folders.

(I ran Parallels uninstaller, but it did not remove ANYTHING.)

I then logged out and in, and reinstalled Parallels. Then installed Parallels Tools.

Now I can still drag from Windows to Mac. But dragging from Mac to Windows works only 1-out-of-10 times. And when it does work, it takes several minutes before the Mac file eventually shows up on the Windows desktop.

An identical setup on my MacBook Pro works perfectly.

I tried to log in to Parallels support, but I can't get in. There is some cryptic form to fill-in, with info I don't have. I purchased TWO Parallels 4 installations just one month ago, but Parallels will not let me in.

I need help and a fix.

Thanks.