Saving Product Without Sale Price Produces Error

Trying to save a new product WITHOUT a sale price produces the error: PHP Warning: array_map() [function.array-map]: Argument #2 should be an array in C:Inetpubvhostsfishandgamegear.comhttpdocsGearStorewp-contentpluginsmarketpressmarketpress.php on line 1870.

And the product data does not save to the database.

Known bug? Workaround? Fix?

This is MarketPress Pro Version 2.5.9 running under WordPress 3.4 on a Windows IIS server.