Error Opening Group File can be several issues, here are some tips to eliminate or minimize the frequency of the error message:
Tip #1
1) Open the Printers and Faxes.
2) Right click on the MultiChax Virtual Printer and select Printing Preferences.
3) Click on the File Formats Tab and change your options like below (note: Disable Image).

4) Click OK to save and close the Printer Preferences.
5) Open QuickBooks (or any accounting program) and select Printer Setup, highlight form name “Check/Paycheck” and select the MultiChax Virtual Printer.
6) Click on Options for the Virtual Printer, and select the file formats tab.
7) Change the settings to match the setting above (note: Disable Image).
8) Click OK to save your settings.
WARNING: The following tip is for ADVANCED USERS ONLY. It requires you to make changes in the system’s registry, which could disable your machine if done incorrectly.
Tip # 2
1) Click on the Start Menu, and select the RUN command.
2) Type in “REGEDIT” without the quotes.
3) Click on the “+” symbols for HKEY_LOCAL_MACHINE, then SOFTWARE, then MULTICHAX
Path is “HKEY_LOCAL_MACHINE\SOFTWARE\MultiChax\SearchInterval”
4) Click on the Search Interval Key, and double click on the “AB Default” icon on the right hand window panel.
5) Change the search interval field from “5000″ to “30000″ like the image below:

6) Click OK, and close the REGISTRY EDITOR.