Sansa:
Here are a few troubleshooting items that can help.
It is hard to debug on a specific PCs, you should try an other PC.
Reboot may help in fixing the problem, by closing any conflicting programs.
Any new recent software might conflict with ShowMyPC.
Any other use of VNC viewer can conflict with ShowMyPC.
Some firewalls or anti-Virus software may block ShowMyPC.