Error pleasewait.exe

This is most likely the remains of a malware infestation.

Before anything else, let's see if there's any malware left...

Please download and install Malwarebytes Anti-malware (free version) from http://www.malwarebytes.org/products/malwarebytes_free/ - UNtick 'Enable free trial of MBAM PRO' at the end of the installation - and update it, then run a full scan in your main account, and Quick scans in any other user accounts.

Delete everything it finds

Are you still getting the 'pleasewait.exe' error?
If so, open MSCONFIG and look in the Startup listing, See if you can find it listed there. UNtick it, and post its details in your response, then reboot and see if the message has now gone.