Dual Twinhan's fail to work under MP.
For some reason MP uses the highest priority Twinhan tuner in all graphs and hence why recording then switching channels fails.

h4. Steps to Reproduce
The log is attached but here is a quick synopsis...

Working Card 3 filters...
4-11-2005 21:55:12 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Tuner Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_036e&subsys_00011822&rev_11MP1-4&2e98101c&0&48f0#{71985f48-1ca1-11d3-9cc8-00c04f7971e0}\{8771b605-991e-415e-a8e3-9cd234520ba7}>
4-11-2005 21:55:12 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Capture Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_0878&subsys_00011822&rev_11MP1-4&2e98101c&0&49f0#{fd0a5af4-b41d-11d2-9c95-00c04f7971e0}\{603a0ce4-13f6-44a2-8480-9b6a63f1f903}>

Failing Card 4 four chosen filters...
4-11-2005 22:50:02 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Tuner Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_036e&subsys_00011822&rev_11MP1-4&2e98101c&0&48f0#{71985f48-1ca1-11d3-9cc8-00c04f7971e0}\{8771b605-991e-415e-a8e3-9cd234520ba7}>
4-11-2005 22:50:02 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Capture Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_0878&subsys_00011822&rev_11MP1-4&2e98101c&0&51f0#{fd0a5af4-b41d-11d2-9c95-00c04f7971e0}\{603a0ce4-13f6-44a2-8480-9b6a63f1f903}>
Note: The Tuner filter is the same as Card 3.
Then MP connects with this Capture Filter...
4-11-2005 22:50:03 DVBGraphBDA: try:@device:pnp:\\?\pci#ven_109e&dev_0878&subsys_00011822&rev_11MP1-4&2e98101c&0&49f0#{fd0a5af4-b41d-11d2-9c95-00c04f7971e0}\{603a0ce4-13f6-44a2-8480-9b6a63f1f903}
The connection works but this is also from Card 3
So you get...
4-11-2005 22:50:03 DVBGraphBDA: FAILED unable to start graph :0x800700AA

Again further on in the log it tries Card 4 again and connects first time...
4-11-2005 22:51:25 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Tuner Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_036e&subsys_00011822&rev_11MP1-4&2e98101c&0&48f0#{71985f48-1ca1-11d3-9cc8-00c04f7971e0}\{8771b605-991e-415e-a8e3-9cd234520ba7}>
4-11-2005 22:51:25 DVBGraphBDA: Added filter <DTV-DVBS 878 Digital Capture Filter> with moniker <@device:pnp:\\?\pci#ven_109e&dev_0878&subsys_00011822&rev_11MP1-4&2e98101c&0&49f0#{fd0a5af4-b41d-11d2-9c95-00c04f7971e0}\{603a0ce4-13f6-44a2-8480-9b6a63f1f903}>
Note: The filters match those of Card 3 - hence it fails when starting the Graph.

Another Conexant based chipset problem to deal with on DVB cards.
I guess on Card 4 with the first failure instead of trying the other Capture Filter it needs to try the other Tuner filter instead in this case.

h4. Additional Information
This has been reported with DVB-T cards as well.