Update: today I've tested a couple of timelapses, but the camera stopped imaging and now, if I try to shot I get Error 99 (a generic code) and the shutter makes a different noise (mirror up but curtain closed).
Since I've installed the chdk yesterday, is this the cause? How to solve?
it's probably not the hack itself. i often had error99's on my 350d which is why i stopped using it a year ago or so, before i ever tried the hack. it just stopped doing it when i dug it out the other month which is when i thought i'd try the hack.
from what i remember when i was looking into error 99's before it's related to lens communication, shutter or not enough power to the camera. u can try cleaning battery and lens contacts with a clean/new pencil erasor and make sure your battery is fulled charged.
nothing in the hack is permanent (apart from making it look for the autoexec.bin file, but even that can be reversed) so if it was related to the hack it would go away when u powered the camera off and on again. the times i know that i did something stupid with my own code (null pointer etc) the camera usually gave me an error01 not error99.
which version are you using? i think i based my code off 350D-20101011 and did fix a few things that *may* have caused me some errors sometimes, tho since my camera does sometimes gives an error99 anyway it may just have been my camera being a bit faulty. i bought it 2nd hand from ebay cheap with the AF broken so guess it wasn't looked after too well.
i can upload my version without the ramping stuff in (as it's not finished) if you wanted to try that.
edit: error99 and shutter life is one reason why a point and shoot may be better suited to timelapse stuff anyway