This error sometimes occurs when the XML file which saves all the playlists has been corrupted.
To repair this issue, perform the following process:
1. Close Monitors AnyWhere.
2. Click on Start > Run > type in "%programdata%" > go to "Greenware Technologies" folder >
Locate and delete the file: ComboParametersCache.xml
3. Open Monitors Anywhere again and try to add a new task.
If that does not work, repeat steps 1 & 2 above, then locate and delete the file: ComboFullPathCache.xml