really weird but very frustrating issue. i had this the last time i tried updating templates too, around the turn of the year.
when i try and upload my images.zip files, the images referenced in the html file rarely are ok. the error i get is that the system couldnt find the images files, and can i add them to the zip and try uploading again.
the zip file is definitely ok. what i found was that when i exported my earlier template from your site, the time of the images inside the zip file are approx 8 hours in the future, approx the difference between oz and uk time. this is the case in both ubuntu linux 8.10 and windows xp. previously the only way i could get campaignmonitor to recognise the updated image files in the zip file, was to move the files to a different pc, and make the pc clock run fast - so that the files seemed newer than the times that cm was exporting. that way the images in the zip and the zip itself ran fine. i know this sounds crazy, it happened in late dec last year too, there is another post of mine in the fourums concerning this.for whatever reason i cant get this to work today. i've spent 2 hours trying to simply upload 2 updated images to my template. this is exactly the same issue as i contacted the cm support about around christmas time, but they couldnt replicate it or come up with an answer.
please help ....
I have exactly the same issue - I'm in GMT and also using Ubuntu.. I've emailed support.. need a fix.