Error : 1062 - Please Help

I transferred my forum to a new host. Now when I post a New thread or New Reply I get the following error:

Database error in vBulletin 3.8.1:

Invalid SQL:

				INSERT INTO postlog
				(postid, useragent, ip, dateline)
				VALUES
				(280730, 'Opera/9.80 (Windows NT 5.1; U; en) Presto/2.6.30 Version/10.62', 1976013126, 1286406175);

MySQL Error   : Duplicate entry '280730' for key 1
Error Number  : 1062
Request Date  : Wednesday, October 6th 2010 @ 06:02:55 PM
Error Date    : Wednesday, October 6th 2010 @ 06:02:56 PM
Script        : http://myforum.com/forum/newthread.php?do=postthread&f=27
Referrer      : http://myforum.com/forum/newthread.php?do=newthread&f=27
IP Address    : XXX-XXX-XXX-XXX
Username      : admin
Classname     : vB_Database
MySQL Version : 5.0.91-community

Code (markup):

This pops up after I hit the submit button for a New Thread or New Reply. It doesn't do this with quick reply. It does post the thread or post. Any thoughts on how to fix this?

 

Thanks for your advice Shawn, my forum is working now.