How to reduce crashes in Win7 64 bit Pro

LO Calc is crashing regularly and becoming annoying. Not an overly complex file: 6 worksheets with some pivot tables, imported from a bookkeeper’s Excel file. Crashes happen upon entering data in cells.
Typically I can work for up to an hour or so, then there’s another crash. Even though I’m saving after every data entry into a cell, the crashes usually lose my last two or three entries.
Any suggestions for remedies appreciated. Thanks.
Libre Office ver.
Windows 7 Pro 64 bit
Intel Core2 Duo @ 3 GHz

I’m also having this same problem.