Please switch template to one of joomla default ones and check if it works than. If it does than send me an access to joomla panel and ftp. If not than You need to report it to Virtuemart support.
I have an answer from programmers and I'm afraid what I've adviced to rename the file is the only option. We do not support joomla 2.5 for some time already and most probably newest VM does not come along with outdated styles. Sorry.
I fixed it by copying /html/com_virtuemart/cart folder from storebox template into the instyle template. Weird, but it worked. I hope I don't run into future problems with this since there is no solution and I'm using a work around.
I'm glad it's working, but I must say I can't believe the solution You did Great job. This files are based on standard VM file, so You should not have any problems using this one.