Be sure to have a Windows Aero Desktop Theme enabled. What you describe with the dialog boxes is a symptom of having it disabled?
Also make sure you have your Windows Power Options set to High Performance in the Windows Control Panel.
Are you running an approved graphics car driver from the SolidWorks website?
What CPU did you spec with your system? The CPU has a big affect on the overall computer performance including the graphics display capabilities.
How feature rich and big are the assemblies you are creating in SolidWorks? The Quadro 400 (assuming that is not a typo and you don't have a Quadro 4000) is a bit on the light side for SolidWorks. If you are working on big assemblies and like to have a lot of files and programs open all at once that could be an issue for you.
Thanks for replying Anna.
I have in the past, always set my PCs to 'classic' theme to minimise memory use and avoid superfluous graphics gimmicks such as zoom boxes (and as I can now see in Aero mode, translucent title bars).
Yes the card is a Qudro 400 (no typo), it is what our IT guys supplied.
I now have the Aero theme set and Solidworks seems to be more settled.
Thanks once again.
This also happens with AMD cards.
Found this post and it fixed the problem i had with one workstation (that person had classic look enabled)
So the Aero theme has big rounded corner buttons.
Sadly the file name is truncated to 3 characters, and it is the 4th character that is the difference between these two files!
Fortunately I have discovered that right clicking on the title bar of the file gives the full file name on Solidworks title bar.
One step forward, two steps back.