Steps to reproduce: * Enable the pref browser.sessionstore.resume_session * Close Firefox * Start -> Run... -> "http://www.mozilla.org/" -> OK Expected result: Firefox starts with the previous browsing session and one additional tab. Actual result: Additionally either the message "Couldn't run 'http://www.mozilla.org/'. ..." (or something alike) or a tiny, only half way initialized window (about which SessionStore complains that window.document.documentElement has no properties). A work-around is to disable DDE through a registry hack (since the supportDDEExec pref doesn't work - see bug 192286). Not sure whether this is also related to bug 269033.

Just to be sure: I don't think this is related to SessionStore other than that it exposes the issue. AFAICT, the actual problem rather lies with the DDE code.

I tried this on WinXP with the Beta 1 candidate build, and could not reproduce the problem. I got the expected result. Simon, can you please attempt to reproduce this again and see if the problem still exists?

I've looked into it and found that the DDE keys don't normally exist when Firefox isn't running. The issue was that Firefox had crashed under the administration account and couldn't remove those keys when run under my usual LUA. I've filed bug 344481 for that issue.