I have an i7 GPU as well as a NVIDIA Optimus GPU and I searched on the forum saying that I must allow the GPU to autoselect which GPU to use for MSN. That setting is already set to autoselect in the NVIDIA control panel, however I still cannot load Messenger Plus with MSN. I've tried reinstalling many times.

Core i7-2630QM
8 GB RAM
256 GB SSD
NVIDIA GeForce GT 555m
Windows 7 x64 Professional

Messenger Plus worked fine on my previous dual GPU set up (i7 GPU and ATi 5470). How can I fix this?

The same problem here. (And my two mates have this problem too...)
Core i7-2630QM
8 GB RAM
NVIDIA GeForce GT 525m
Win7 32 bit and with 64 bit too.

Like also said in those threads about the nVidea problem: uninstall everything from nVidea except for the drivers. Quite often there are tools installed together with the drivers which you actually do not need at all. It are those tools and side-programs which often cause trouble in software (not only with Messenger Plus! btw).

Also, try to either update or either downgrade the nVidea driver version.

I read it, and I tried it already, no success

I have plus only without nvidia driver installed

me too

Did you try downloading the latest Messenger Plus! version, 5.03?