Excel 2000 won’t word-wrap whole entry

This one is driving me crazy and I can’t find any MS documentation about it. I have long text entries in a spreadsheet. I format the cells with Alignment set to Wrap. For 98% of my cells, that works just fine. Then for no apparent reason, I put in a particularly long entry, and after 30-40 lines of wrapping correctly, the wrapping stops. The lines run off the edge of the cell (invisible because adjacent cells contain entries). Is there a maximum # of characters that Excel can “handle”? Is this a known bugaboo in Excel 2000? Help! I’m going to have to paste the whole thing into Word to get the printout I need…