Wireless disconnects at random after upgrade to Ubuntu 10.4

Question

After upgrading my home server from Ubuntu 8.10 to 10.4 my wireless seemingly drops out, even though my IRC client keeps it's connection to the servers, so it looks like the machine just stops taking wireless requests. A ping will give a me this

Request timeout for icmp_seq 27

ping: sendto: Host is down

After a while the machine just starts responding again, without any interaction from me. When the machine comes back, this is what dmesg gives me

[ 18.296288] wlan0: direct probe to AP 00:1b:63:22:a4:5f (try 1)

[ 18.296350] wlan0: deauthenticating from 00:1b:63:22:a4:5f by local choice (reason=3)

[ 18.296440] wlan0: direct probe to AP 00:1b:63:22:a4:5f (try 1)

[ 18.298697] wlan0: direct probe responded

[ 18.298706] wlan0: authenticate with AP 00:1b:63:22:a4:5f (try 1)

[ 18.306836] wlan0: authenticated

[ 18.306886] wlan0: associate with AP 00:1b:63:22:a4:5f (try 1)

[ 18.309396] wlan0: RX AssocResp from 00:1b:63:22:a4:5f (capab=0x411 status=0 aid=2)

[ 18.309402] wlan0: associated

[ 18.310187] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready

[ 18.447742] apm: BIOS version 1.2 Flags 0x03 (Driver version 1.16ac)

[ 18.447748] apm: overridden by ACPI.

[ 19.163282] padlock: VIA PadLock not detected.

[ 28.352022] wlan0: no IPv6 routers present

kjes@brin:~$

lspci

02:07.0 Network controller: RaLink RT2561/RT61 rev B 802.11g

It's on a wireless network with WPA2, the machine worked without any problems on the same wireless network since Ubuntu 8.10 was the most resent version, and there have been no changes to my network recently. Even though the server drops out, everything else on the network keeps working like normal.