Not enough system resources???

[seenfresh]

I am having an issue while using Excel 2007 xlsm. My Wsheet has over 50,000 rows of data. When I try to delete a row an error message appears stating unable to perform not enough system resources available. I have no external references or formulas evident. When I move to a row near the end of all my data I am able to delete a row, but when I move to row ...say (25,000) and try to delete a row I get the error message...

Has anyone experienced this before? Any advice or help would be much appreciated!

Thanks in advance,