Comment 57 for bug 575492

This problem has also reappeared for me. (Ubuntu 11.04 64bit)
I have to press the wifi button on my laptop to turn my wireless card on and off about every 20 minutes to keep the connection alive and be able to ping my router.

04:00.0 Network controller [0280]: Intel Corporation WiFi Link 5100 [8086:4232]
 Subsystem: Intel Corporation WiFi Link 5100 AGN [8086:1321]
 Flags: bus master, fast devsel, latency 0, IRQ 48
 Memory at f8000000 (64-bit, non-prefetchable) [size=8K]
 Capabilities: <access denied>
 Kernel driver in use: iwlagn
 Kernel modules: iwlagn