Anyway, i can't understand why online play can produce such bugs.
Can you test this:
Click on Start - Run - type "dxdiag" and click OK
Open the "Sound" tab and put hardware acceleration to zero.
Close dxdiag, lauch LFS and try again...
If the pb occurs again, we can maybe try this:
Click on Start - Run - type "msconfig" and click OK.
Open the "Startup" tab and click on "disable all"
Click OK, restart your computer and try again LFS