Can’t Add/Delete Plugins or use Plugin Browser

Ok – very weird problem:

1) I can activate and deactivate plugins that already exist in the plugins folder.

2) If I delete a plugin folder (active or deactivaated) or ADD another plugin folder to the plugins directory via ftp and I go back to the plugin screen in admin I get a blank white screen. There’s no error message. As soon as I reverse whatever I plugin folder I added (or deleted) – admin is fine again. THE WHITE SCREEN PROBLEM DOES NOT HAPPEN if I add/delete a single php file plugin like hello dolly – I can add and delete it without a problem.

3) If I try to use the plugin browser (ie click on the link at the bottom of the plugin screeen) – I get the admin header, the menu down the left side of the page to the Plugin menu item and the rest never loads.

4) The site was not recently upgraded – however we did change hosts a couple months ago – moved to a Unix/Linux/Apache host from a Windows Host.

Other than the problem above the site is working perfectly.

Any ideas? I’m out of them – I’ve tried file permissions and looked through the database.

Thanks,
Lydia