kspread locks up on seemingly simple spreadsheets (1.4.2/kde 3.4.3)

I run kde-3.4.3 on an IBM Thinkpad T30 (P4 2GHz 1GB) running FreeBSD 
6.0-STABLE.  I have a fair amount of problems with relatively simple 
spreadsheets causing kspread 1.4.2 to wedge.  By relatively simple, I 
mean no heavy math, just +-*/.  The simplest spreadsheet that causes 
this problem is essentially a "check register" type of application, 
where a given row takes the previous row's balance, adds some numbers 
(there's an IF(a;b;c) involved), and produces a new balance for that 
row.

A more complex, but highly similar form is a mortgage history 
spreadsheet I use, which starts with a beginning mortgage balance, 
calculates each months' interest principal and escrow, and produces a 
running total of declining principal balance, interest paid for the 
year, and escrow balance.

The first (simpler) example is new, but the mortgage spreadsheet used 
to run under kde 3.I forget, but probably 3.3 or earlier.  I can no 
longer open this spreadsheet, which means that my records are 
essentially lost unless I can get kspread to behave, or migrate to 
other software which can read kspread files.

I welcome suggestions as to how I can troubleshoot this and regain 
access to my valuable data.

Thank you!

Jim