what anti-virus program are you using?
from 4.7 i'm assuming you are talking about messenger plus! live. there are no viruses within the program, it is safe to use with or without the sponsor program. you have an option of installing it without the sponsor program.. at the beginning of the installation you are given the option.
make sure you download the program directly from this site!
http://www.msgplus.net/
i do not think that plus! has anything to do with your speakers not working.
here are some tips:
make sure you haven't accidentally "muted" anything (Programs -> Accessories -> Entertainment -> Volume Control).
make sure you have the right "environment" selected. if you have one speaker, two speakers etc. (Control Panel -> Sound & Audio Devices -> then under "Speaker Settings" hit the Advanced button)
did you install the drivers for your sound card?
did they work before but are not working now?
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