For what it's worth, MJ isn't the culprit. The MJ client only calls out, and only to MJ's servers, and only for MJ management and operation purposes.
MJ has no way to invite a trojan or worm into your system. The only way that MJ can be connected to your problem is if you forwarded any ports inbound through your router to your PC in the belief that that could make MJ work better. In that case, MJ is still not the culprit.
A little good new for US computers,This quote from ComputerWorld Security.
"As of Monday, 45% of the Conficker.c-infected computers were traced to Asian IP addresses, while another 31% were pegged to European addresses. South America accounted for 14% of the total, and just 5.8% of the infected PCs were using IP addresses associated with North America"
They also say the most likely place of origin is China.