。
She had trouble with him before.
Literal
She [topic-は] before him [with-と] problem [object-を] caused.
問題を起こす ('to cause a problem') is a common collocation built on 起こす ('to raise, set up, cause'), which has a wide range of trigger meanings — 起こす also produces 事件を起こす ('cause an incident'), 火事を起こす ('start a fire'), 訴訟を起こす ('file a lawsuit'). 以前 ('previously, formerly') is more formal and explicit than 前 ('before'), often appearing in written accounts. The と marks the comitative — the trouble was something that happened jointly with him, often implying interpersonal conflict rather than just being near him when something happened.