This is an issue known to mediamonkey
This appears to be due to an issue with support for iTunes 9 the iPhone 3.0 firmware as the DLL is Plugin used to support this
If you don't use these you can get things running by deleting or re-naming the .DLL file (mediamonkey needs to be not running)
or there is a new version of the file available here ...
MediaMonkey • View topic - d_iPhone.dll supporting iPhone 3.0 firmware
a quick search will find many mentions of this issue so you may want to have a look -
mediamonkey d_iPhone.dll error - Google Search
I'm using the program fine on Windows7 RTM, I can't remember doing anything with this file but I may have