I posted this on another forum, but it may apply to your rebooting/freezing problem, you might want to test if it's your sd card before doing the Factory Data Reset:
A bad file/filesystem on your sd card can also cause a boatload of problems on a device, certainly everything the OP has described.
If you have a spare sd card, put it in your phone and the problems should go away if something on your original card was not right. If you don't have a spare, take the sd card out of the phone and test it without the memory card.
If it is the card causing the problems, transfer the contents of your card to your PC and reformat the card in the phone. Then move only essential files and folders back to the card and test for a while. Repeat in small batches until you have found the bad file or all of the files/folders that you want are back on the card. If you don't find a bad file, don't worry, it was probably something wrong with the filesystem (FAT, File Allocation Table) that was causing your device's problems, the formatting of the card would fix that.
Do you remember doing something file related at the start of that 2 week period, like downloading some picture files, or videos, etc? Are you also having problems displaying pics in the Gallery app?