More experience the same problem, see
Error with v.3.61. Only happens on MSNM 7.5.0306.
So you can do two things...either not use Plus! till Patchou solved it or downgrade to MSNM 7.0.0816 (available where you normally download MSNM, just alter operating system - Win2000 for an XP compatible version - after you clicked "download").