Unlikely but it is possible that there are problems with the version of Mach3 that you are using.
By popular opinion, the best version to be using is R3.043.062 and it can be downloaded from here
ftp://anonymous:guest@machsupport.com/Mach3/Mach3Version3.043.062.exeSome information taken from the Downloads page…
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.
Tweakie.