Mackie Control surface unresponsive intermittently

Hi - has anybody else had issues with the MCU being unresponsive intermittently?  I've experienced this with 8.5.3 and now with X1b.  The issue generally manifests itself when opening a project - sometimes it seems to take 5-10 seconds after a project has been opened (and after the faders have adjusted for the new project) to operate.
 
I'm running the Mackie MCU via USB.  I am running an old BIOS on the computer though - everytime I update the BIOS, the computer can no longer see my UAD1 pci card, so am running the older one  - hopefully that's not affecting the MCU performance.
 
Other specs are: Win7 x64, Sonar X1b x64, UAD1 pci, RME Fireface UFX running via Firewire with latest firmware and drivers.  I'm running the latest firmware on the Mackie Control Universal (although it seems quite old).  Hardware is: Dell Precision T7400 - Dual quad core Xeon 3.2 Ghz, 8 Gig RAM and 3 hard drives.   
 
Thanks!
Russ
 

I'm using a MCU PRO and C4 thru USB and so far it's all good, I haven't noticed any drop outs,   If only the rest of the Prochannel was available to control, I'd been running around giving random hugs to everyone.

Thanks all - apologies for the late reply - was out of the country last week.
 
So it sounds like it's my configuration since others are having similar issues.   For clarity, I'm using the default Windows 7 USB driver & just have the MCU MIDI input and output enabled for use.  Is there anything else I need to do?
 
Thanks for your help.
Russ