I had this problem aswell, every text I received was at 22:33 on 20 May 2043!!!!!! I removed the battery whilst the phone was switched on, waited for a minute then put the battery back in. It was fine after this....
@High-Flyer : Yes, your post is actually is ! :-)
Yesterday, after changing the device's time manually, I rebooted my BB by holding Alt + R.Shift + Del. Since then, all the sms that I received, showed a timestamp in the future. I rebooted my device once more this morning, with time correctly set. After this second reboot, everything becomes normal again !