FAME FILES: Beyonce's Dad Mo Money Mo Problems

Beyonce's dad is rolling in money problems -- on the heels of accusations he's a deadbeat dad ... TMZ has learned he's being sued, ironically, by a company that used to handle his cash.

According to the legal docs ... a credit bureau is trying to collect $64,587.14 from Mathew Knowles -- money it claims he owed to an accounting firm he hired.