I have a new focusrite saffire 26 I was having connection problems using a via chipset firewire card (a known problem with focusrite and windows 10) so I purchased a TI firewire card connection problem solved or so I thought. the saffire is found fine and works with everything untill I start up sonar, I can see it in the devices audio input and output but as soon as I load a track or song I loose connection and the light on saffire flashes meaning connection lost, when I then check to see if the inputs and outputs are still there in the devices of which they are connection is re'established the min I exit devices I loose it again. Help please.

Sorry can't answer I don't know diddly about firewire,,, but Focusrite Support is very good about troubleshooting and usually get back to you right away on weekdays.. 
My guess is the issue will have nothing to do with Sonar. 
Run the firmware updates for the Focusrite. 

I assume you read this:
 
https://support.focusrite.com/hc/en-gb/articles/207546925-How-can-I-tell-if-my-Firewire-chipset-is-compatible-with-my-interface-
 
What model of FW card did you buy?

Texas Instruments recommended by focusrite

Frankyfinch
Texas Instruments recommended by focusrite

That's the chipset, but there are many different models.  Not all Texas Instruments chipsets are the same, which is why I asked for the model name.... What is the model (What does it say on the box)?

Senda SE-PCIE-1394B whatever that is I've just tried it with an old ver of ableton live I had lying around and it works fine I've also tried it with stand alone guitar rig and addictive drums and it works fine seems to be a sonar problem.

O

Frankyfinch
Senda SE-PCIE-1394B...

Okay, according to Focusrite it has the most recommended TI chipset, so that should be fine.
 
Let's back up a bit.  You say your problems start when launching Sonar... What happens if you just use the Saffire 26 like a regular sound card -- say, playing music, YouTube, etc.?

That all works fine it's only when I enter a track or a song iv been working on. I can play music I can use stand alone software that came with sonar ie: addictive drums and guitar rig and iv used it in an old ver of ableton live just to see if it worked with other music software and it was fine. I can open sonar and everything checks out drivers are there all looks fine but as soon as I open a project or a track in a new project the connections lost.

I'm not a computer wiz but wondered if the software is conflicting with a driver if that possible.

Go into Device manager and make sure the onboard firewire is disabled.  This may be obvious, but you do have the Saffire plugged into the new firewire card (and not the onboard port), correct?
 
Go to Focusrite's site and donwload the latest drivers for the Saffire 26.  Do an uninstall/reinstall of your Focusrite drivers.  (Make sure to disconnect your Saffire first  --or power it off if it has an on/off switch).  Reboot.
 
Finally, if it's still having problems, take a look at this which involves getting the legacy firewire drivers to work in Win 10:
 
http://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_devices/windows-10-and-ieee-1394-firewire-legacy-drivers/27ae7f1b-c307-4159-802e-61a123d0de87?page=1&auth=1