iPhone 4 won't sync with iTunes

[iProg]

Up until last night, the last time I connected my iPhone 4 to my computer to sync was October. Now when I connect to the computer, iTunes says "preparing to sync step 1 of 6" for a while and then I get an error message from the computer that says my iPhone could not be synced because the sync failed to start.

I have looked at all my settings (obviously I must be overlooking something), and I have restarted the computer, iTunes, and my phone many times, but the results are always the same. The software for iTunes and the phone are up to date.

I hope someone can help me figure out what the problem is. I'd like to get the digital copies I've downloaded into iTunes onto my phone.

Thanks.