Yea thats a problem for me aswell, and I have to uninstall a plugin :/
Joomla 1.6.3
If I try to refresh the page I get the browser resend box as if I passed a query to the plugin filter form despite the fact I didn't!.
I hope someone manages to fix this.
[EDIT]
Having performed another google search on the issue I found this bug report for Joomla 1.6:
[REPORT]
Open Date
2010-07-02 05:30:46
Close Date
2010-09-12 10:36:48
Submitted By: Jean-Marie Simonet
Adddate: 2010-07-09 02:48:52
Some of these are corrected as of Revision 18060.
Would something similar to what we have now in Installer/manage fit?
**There are no extensions installed matching your query**
[/REPORT]
[SOURCE]
[url="http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=21288"]Bug 21288[/url]
[/SOURCE]
As you can see it was a reported bug some time ago and the report has been closed as fixed, therefore no one at present is working on the issue, nor where any of the fixes published to the tracker

I have used the manage part of Joomla recently to uninstall a module without issues, I have tried clearing the cache and logging back in with the same error.
Does anyone know how to manually unpublish a plugin ?
[/EDIT]