Running Ubuntu 12.04 I'm facing to this bug too on a regular base:

dmesh | grep "SW error"
==>
[79153.416131] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79154.114339] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79182.601542] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79210.393437] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79239.639635] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79271.724168] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79305.377365] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[79556.166466] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79581.053733] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79621.110023] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[79656.511322] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79693.461862] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79731.628843] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79770.989061] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79810.106815] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79848.813199] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[79886.355233] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79925.156145] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[79964.960656] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80004.916408] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80041.439102] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[80114.354849] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80116.112521] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80156.078380] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80199.550325] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80236.945657] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80277.606785] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80318.433224] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80358.833199] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80400.162497] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80437.868621] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80479.276478] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80519.363035] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80561.013492] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80600.076921] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80633.357018] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80665.502634] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80707.912118] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80744.013560] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80784.738038] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80824.861209] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80868.425019] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80909.828595] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80952.598155] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[80995.129716] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[81035.985741] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[81082.097862] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[81123.727590] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[81167.010386] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.
[81206.536073] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[81365.946253] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[81424.288247] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x2000000.
[82059.914618] iwlwifi 0000:25:00.0: Microcode SW error detected.  Restarting 0x82000000.