I would be inclined to re-install Mach3 (save a copy of your existing Mach3 folder first) but not the latest 066 version - perhaps version 062.
Tweakie.
The official info...
When available, updates for Mach3 and the Add-ons are posted on the Downloads & Update page. To update to the newest version, follow the procedure below:
1) Backup the following to the desktop, or even better, a USB drive:
XML(Profile) – This stores you’re settings for Mach3, if you lose it you will need to re-setup you’re ports and pins, motor tuning, etc.
Screensets/Macros/Brains
2) Download the current version of Mach3 from the Downloads & Update page.
3) Install the downloaded version; allow the install path to default to where Mach3 is installed.
WARNING: If you do not backup the files in Step 1, you will lose ALL settings and configurations.