Hi Mauno,
Thanks for taking an interest in the current Fire_bug version 1.3 problem... Here is a full description of what happens in my FireFox (version 3.0.6) with Fire_bug version 1.3 installed (running on Windows XP).
See attached screenshots which illustrate the process.
Please note that I am experiencing the problem within Moodle courses, not when downloading files on the Web in general.
In one of my moodle courses (local install, but the problem also occurs on distant moodle sites) I go to Files and try to donwload a file which I have previously uploaded there. Small files usually download OK. So I try with a large file, eg HotPotsWorkshops.zip (27.5 Mo).
#1 The download manager popup window appears and shows download progress, which halts at 25.7 with message "A few seconds remaining". Nothing happens, so #2 I click the Cancel (Annuler) button and immediately after #3 I click the Try again (Réessayer) button. The download quickly resumes and finishes OK.
I have tried your suggestion of increasing dommaxscriptruntime from its original value: 10 to value:100. Things get worse (see screenshot 4: now the downloading process halts even earlier than with old value of 10... (#4)
#5 Then I tried to download another large file, a flash .FLV file. This time the download process does not even start, it freezes on Starting (Démarrage) message. However, clicking the Cancel then the Resume buttons enables the download process to work OK.
If someone a) experiences the same problem and b) can understand it and provide a solution, it would be nice. In the meantime I'll take Mauno's advice and have a cup glass of tea whisky to drown the bug.
Joseph