Inserting documentnumbers causes SAP Business One to crash

Hello,

I am implementing SAP Business One for a customer at this moment. The customer asked me to make a new serie of documentnumbers for every document per month.

When inserting the new series, SAP crashes (sometimes with a error, sometimes not) and it didn't save the updated series I made.

Does anybody know a thing about this problem? And is it possible to add the series by DTW?

I am working with patch level 42 in SAP 2007A.

Looking forward to your reactions,

Greetz

Hendri