I've only had this happen once and it was a connection problem.. My internet was so slow that it was just barely connected. I could pretty much do everything but nothing was registered on the server end, just on my side.
Anyway, other then your connection, assuming it's fast enough, you could try clearing your internet cookies and cache and also clear your Flash cache
. This link is on DDT but it helps with crystal saga too. Also make sure your flash player and java script are up to date.
It sounds like a flash memory problem or connection problem to me. You can try using a different browser (like chrome firefox, waterfox, cometbird, safari, opera, internet explorer, etc.) or using a different computer entirely to see if it resolves the issue.
Hope this helps.~