Hi
Try starting your Disk Utility and check / repair Disk permissions. Then clear sl cache restart and try.
The SL viewers seem pretty succeptable to disk flakiness. This could've occurred when you had that sunflowerbed app go weird.
If doesn't work, restart your mac from an alternate boot disk (Install DVD, ext hdd etc) or if a recent mac hold down Option key when startiong the mac, choose the recovery partition. Then run Disk Utility and choose Repair Disk.
HTH