nightmare i.e.

i need serious good advice .i've spent the best part of seventy quid on bandits who say they can fix my explorer problem .yeah right!
briefly,when i boot up i get over one hundred error messages before my start up page appears.this takes about twenty minutes.most of the messages refer to mssn.exe.
explorer keeps crashing and the only way to get online is to go thro the microsoft error reporting service.
the only clues i have are mumbling from one of the bandits about trojans,shell dll's and i-mesh.
any advice will be greatly appreciated and admired