suddenly...i can't do backups

[bwnvideo]

nothing's changed, nothing's been updated or upgraded and I've done updates routinely and as of a few days ago suddenly i get this error message when I click on backup:

This webpage is not available.

The webpage at http://www.bwnvideo.com/forums/admin...hp?do=sqltable might be temporarily down or it may have moved permanently to a new web address.

More information on this error
Below is the original error message

Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error.


I'm using 3.6.8 patch 2; I've been afraid to update it to a newer version since I've got lots of custom design on it and the guy that did it for me the first time vanished into thin air but don't know if that would be the problem, it's been running fine so far and I didn't see much reason to upgrade.

I'd like to get someone I can trust to do some other tweaks to this anyway, but not sure how to go about doing that. Anyway, any idea why this would've suddenly happened appropo of nothing?