Hi Omar,
Interesting. I know of a client that was having this problem on the sales side. In that particular instance they were using a third-party product that consolidated SOP invoices. I think it was Sales Document Consolidation from Binary Stream.
Until you get an answer (I'll ask the client if they ever got the problem solved), how about changing your company posting accounts (tools > Setup > Posting > Posting Accounts) in the Sales series. Change the Commissions Payable and Commissions Expense accounts to a clearing account. The entries will offset and your people won't have their posting interrupted.
Are you running any 3rd party products that integrate with the sales module?
Kind regards,
Leslie