Comment 6 for bug 373680

I also have this problem and it's very annoying.
Every 2 minutes exactly, the wireless network stalls because network-manager performs a network scan.
In some drivers (like the atheros ath9k) this causes the network to completely stall from 1 to 5 seconds.

This bug is already known upstream and there is a bug report in the redhat bugzilla as well:

Upstream Bug Report:
http://bugzilla.gnome.org/show_bug.cgi?id=513820

Redhat Bugzilla Report:
https://bugzilla.redhat.com/show_bug.cgi?id=490493

I have created is a workaround patch that disables scanning if your device is already connected to a network.
This patch is based on a suggestion from Christer Weinigel in the Redhat Bugzilla report, but it's not the ideal solution.
Of course, by using it you won't have an updated network list while connected, but your network won't stall.

I also have compiled packages of network-manager for jaunty using the attached patch:
https://launchpad.net/~volanin/+archive/ppa

In old versions of Network Manager there existed an option to enable/disable scanning, but it was removed.
Related bug report about optional scanning:
http://bugzilla.gnome.org/show_bug.cgi?id=165933