Excel 2010 .xlsm Format Crashing.

[numms]

I have an Excel Macro Enabled workbook that I've assembled with various links to other Excel files. It is a fairly large file used for compiling metrics from various data sources so there are a great number of formulas involved in the cells. I have placed some Grouping levels in columns to hide components of the calculated formula. For example, ScheduleAdherence%, which consists of ComplianceTime / ScheduledTime. For ease of maintaining this document, these three fields are populated in columns V, W, and X, and since the only metric we're going to be looking at daily is ScheduleAdherence%, I have columns W and X grouped on V. I feel this is a basic enough approach and seems to work for the purposes we need it for, HOWEVER... When using the number references in the upper left corner of Excel to expand and collapse the hidden columns, Excel consistently shuts down giving an error message. I have tried a number of different things to keep this from happening, but even directly after a successful save and reopening the document just saved, I still get this error message. Should anyone have any ideas which may help me out, I'd appreciate it very much. While doing them one at a time is fine, it's not what the program is designed to do.

Thanks in advance,

Andrew