Modem troubles

My DSL was upgraded to 1 MBit/sec download (stil 256 KBit/sec upload), and it's been bloody fantastic, however one thing has been spoiling it, the fact my previously very nice Zoom X4 DSL Modem/Router has been buggering up for the past 2 months, just completely randomly locking up and only working after a quick reboot, which is fine when I'm actually here, but if I leave a large download going over night and it locks up I'll come back to find it's downloaded only 10% after locking up an hour after I went to bed, which isn't really acceptable. I've e-mailed Zoom's tech support but no answer back yet.