After installing boost, images are not uploaded in files/imagecache

Title explains it pretty much. After installing Boost module, i have troubles with uploading images. I can upload them, but only thumbnails are saved. Big image in sites/default/files/imagecache is not created. I tried to play with permissions, but didnt work. I have no idea where the problem is. What did boost module change that images cant be uploaded?
What shall I do?
Its critical.
I tried to uninstall the module, but the problem still persists!!!