marketpress error generating 1gb error log every 12 hours!

HI I am having an issue with marketpress. It is putting the following error into the server error logs:

[26-May-2011 16:21:11] PHP Warning: in_array() [function.in-array]: Wrong datatype for second argument in /home/mainstre/public_html/wp-content/plugins/marketpress/marketpress.php on line 736

This is for http://www.mainstreet.us. The Errors are happening so fast that the error log shuts down my server (it crosses the 2gb line) within 2 days.

Help!