Help! Computer loses space when uploading photos to ipad

Can someone help me out?

Last night when I was uploading all my pictures to my ipad (about 15gb worth), I noticed that my computer's free hard drive space was decreasing consistently with the number of pictures synced. I opened finder and literally watched my available space drop from 10 gb to 200 mb, at which point my computer freaked out and popped up all these error messages about needing to clear up space and delete files. The picture transfer also stopped at that point.

Has anybody experienced something similar or knows why this is happening? I was thinking that maybe itunes/iphoto copies the files to a temporary cache space in order to upload them but some bug or error is causing those files to remain as duplicates instead of being deleted afterwards. But shouldn't that be a ram issue, not a hard drive issue? And I've never experienced this kind of problem with my iphone.

I was able to fix everything by rebooting and then reuploading the remaining pics (and then rebooting again), but I would like to fix this problem so I don't have to do that every single time I upload pictures. Also, when I rebooted the final time, I noticed that I still lost ~2gb of usable space.

Thanks!

 

2008 aluminum macbook - 2.4ghz, 4 gb ram, 250 gb hd

 

thanks!!

to clarify - does that mean that it needs to create a cached version for photos already synced, or only new ones? And it sounds like the folder doesn't delete itself once it's done syncing? Guess that means I might have to worry about my free space more in the future..

Also - does restarting definitely clear the cache every time? I'm assuming it does because it seemed to work for me, but it wasn't mentioned specifically in the article