stop using 0.7.2, use 0.8 (it has faster sync time). or use a lite client.
I upgraded to 0.8 about 3 weeks ago, and my balance went to 0, as all of last years received transactions changed to unconfirmed and it started DL blocks from a year ago. Finally enough blocks were DL'd that I had a balance and when I sent it, it went into the twilight-zone.