Avira Windows Application Error

I just installed Avira Free on a laptop running Windows Vista. When I run the system scan, it runs through it but when it's about to hit 100%, I receive a Windows Application Error that reads:

The exception unknown software exception (0xc0000409) occurred in the application at location 0x73d9230e.
Click OK to terminate.


Once I hit OK, obviously Avira closes, and I can't seem to finish scanning. Help!

does malwarebytes run on Win Vista ?;
or,
in the alternative,
does MSFT Security essentials run on Win Vista ?


both are freeware