Could you tell us more about what your program does?

1. Does it create/save/close each workbook one-at-a-time or does it
save all workbooks at once?

2. Does creating a workbook fetch data from a database and format it?
If so,
do you do all the queries once up-front or do you do a new query each
time you create a workbook.

3. Are you certain the stalling issue has to do with memory and not
with an orphaned database connection? (Orphaned database connections
are a certain way to stall a program.)

4. Does each row require special formatting when it's written ? Do you
make the formatting changes a line-at-a-time or all at once?

5. If you're running a 700 Mhz machine (or faster) with a Gig of RAM
(or more) then the problem probably doesn't have to do with memory
allocation. 30,000 is big but not 3 to 3 1/2 hours big. It should take
less than 45 minutes.

How fast is your machine and what is your OS?

If I had to guess the issue has to do with orphaned DB connections.