Never seen this. You can try to reset the SolidWorks registry on that machine.
Close SolidWorks and got to Start > Run > type regedit > go to HKEY_CURRENT_USER > Software > SolidWorks > SolidWorks 20XX
Rename SolidWorks 2014 to SolidWorks 2014-OLD (this is just to keep the backup of existing actually registry file), close the registry and restart SolidWorks. This will essentially reset SolidWorks to its as installed settings, so you will have to set all the options again. If this works, return to the registry and delete the SolidWorks 2014-OLD key.
Using Copy Settings wizard, copy the SW settings from the other PC which are running fine and install those settings to machine showing issue.
But all of these option will change any custom setting you have in Tools > Options, toolbar, mouse gestures, etc. so make sure you take a backup of the settings on that machine too before trying anything.
Thanks, we'll give the registery a try as it is easily reversable.
Any luck with Deepak's suggestion? I believe the dialog truncation is related to your system DPI scale or the SolidWorks "large/med font" scale setting. We have SPR 728171 to address a similar issue in the "Select Configuration" dialog and the solution in SW2015 may resolve your problem too.
Are you operating at 125% or higher DPI system scale, or are you using the SolidWorks font scaling value in Tools-Customize?