I also was on the VMCAS site earlier tonight, and was kicked off right after I tried to save one of my entries. I'm glad a friend gave me the advice to type everything in a Word document and cut & paste it into VMCAS rather than typing everything directly into VMCAS.
Wouldn't it be nice if they extended the deadline one day for each day that the site is messed up? I know, I know, I should have submitted my application weeks ago to avoid these troubles, but seriously - it is pathetic that a website for application to a professional school program has this many problems. It is not like it is a one-time thing either, because the AAVMC apparently knows that their application website is a piece of s**t, and that is why they feel the need to give the little warning about how you should apply two weeks early to avoid problems due to web congestion. They really need to invest in technology that can handle the number of applicants that use the site (which is really only a few thousand, right? We're not talking Google-like traffic here!).
Sorry, enough ranting! Hopefully the site will be better tomorrow.