Tvheadend

Hi,

I used to have a rock-solid setup since I installed XBMCBuntu Eden with TvHeadend: I was recording dozens of programs per day including almost every movie aired on the free channels.
Suddenly, on Saturday at 3 o'clock (24 hours before switching to daylight saving time!), it stopped working: scheduled programs are no more recorded (see screenshot).
The /var/log/syslog file shows a lot of:

~$ more /var/log/syslog | grep tvh | grep Mux
Apr  2 06:38:30 pchc tvheadend[1216]: dvr: Recording unable to start: "Les dessous de la mondialisation": Mux not enabled
Apr  2 06:53:30 pchc tvheadend[1216]: dvr: Recording unable to start: "Wakfu": Mux not enabled
Apr  2 07:18:30 pchc tvheadend[1216]: dvr: Recording unable to start: "Wakfu": Mux not enabled
Apr  2 07:53:30 pchc tvheadend[1216]: dvr: Recording unable to start: "X:enius": Mux not enabled
Apr  2 08:38:30 pchc tvheadend[1216]: dvr: Recording unable to start: "Lou !": Mux not enabled
Apr  2 09:13:30 pchc tvheadend[1216]: dvr: Recording unable to start: "Le dessous des cartes": Mux not enabled

When looking in the web interface, I can see that the useful muxes are indeed now disabled (not by me!) (see screenshot).
If I re-enabled them, I can find the following log:

Apr  2 16:52:36 pchc tvheadend[1216]: dvb: Adapter "DiBcom 3000MC/P" mux autodiscovery set to: On
Apr  2 16:52:36 pchc tvheadend[1216]: dvb: Adapter "DiBcom 3000MC/P" idle mux scanning set to: On
Apr  2 16:52:46 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 746,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 746000000
Apr  2 16:52:52 pchc tvheadend[1216]: dvb: Adapter "DiBcom 3000MC/P #2" mux autodiscovery set to: On
Apr  2 16:52:52 pchc tvheadend[1216]: dvb: Adapter "DiBcom 3000MC/P #2" idle mux scanning set to: On
Apr  2 16:52:55 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "205,500 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 205500000
Apr  2 16:53:02 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 498,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 498000000
Apr  2 16:53:15 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "850,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 850000000
Apr  2 16:53:16 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "F: 506,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 506000000
Apr  2 16:53:22 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 610,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 610000000
Apr  2 16:53:36 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "205,500 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 205500000
Apr  2 16:53:42 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 506,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 506000000
Apr  2 16:53:56 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "F: 594,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 594000000
Apr  2 16:54:02 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 522,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 522000000
Apr  2 16:54:16 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "F: 522,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 522000000
Apr  2 16:54:22 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 746,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 746000000
Apr  2 16:54:36 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter0" tuning to "F: 610,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 610000000
Apr  2 16:54:42 pchc tvheadend[1216]: dvb: "/dev/dvb/adapter1" tuning to "F: 594,000 kHz" -- Front configuration failed -- Bad file descriptor, frequency: 594000000
[...]

Do you have any idea of what may cause these problems?
Thanks