If you can use javaloader, try deleting the offending software (English-French).
If the BlackBerry reboots right away, one after the other, you may find this difficult. Try testing javaloader and seeing if you can "see" the BlackBerry. For javaloader info, do a search on 'javaloader'. Need at least some rudimentary knowledge of a DOS-like command prompt.
Try "javaloader -usb dir" ... repeat the command over and over (you can recall a command at the XP shell via hitting cursor up and hitting Enter again) while the BlackBerry is booting. You might be able to get the listing of files, and then be able to delete the offending files before the BlackBerry reboots itself. The window of time may be annoyingly short (a few seconds), but might end up being enough to execute one command at a time per reboot. May have to keep trying the command repeatedly. Depending on the size of window and how long it takes to reboot, it may take a lot of time to accomplish your objective.
You can also try "javaloader -usb wipe" if you don't mind setting up your BlackBerry from scratch again, though you will have to set it up on the BES server all over again. (If your admins are using BES 4, this may be done wirelessly). This command is likely to kill the reboots the quickest, and it may be less frustrating to simply set it up from scratch again.
There may be no quick solution, so you may have to set your BlackBerry aside.