I stuck my usb drive into my comp at work today and when i tried to run Firefox and Thunderbird portable using pstart (then directly) the .exe file just deletes itself...
The base .exe file in the apps folder is still there but this appears to be a raw version without any portable apps gadgets (or my bookmarks/email for that matter)
Tried copyiong over the .exe files from a friends drive only to have them dissappear again! (tried this like 3 times now...)
note: this thread is also under the thunderbird suport forum