Tested env: jre7 b145, winxp, ff3.5.7
rdp info:
10.133.132.227
 user: tester
 pass: dtf_test


Steps to reproduce:
1) install jre7 b145 promotion build
2) uninstall the jre which is installed just now
3) open firefox, open tools -> add-ons -> plugins, if Java Deployment Toolkit 7.0.0.145 is still there, bug is reproduced.