I've been trying to replicate this since you first posted but failed miserably.
The only thing I can think of is the speed at which you draw the arc....is your system 'quick enough' to capture the fact you are drawing an arc?
What
may be happening is the system not being quick enough to actually 'see' the points between the start and end of the stroke....thus it only has a start and an end so only calculates between those two points....possibly.
Do you have anything running in the background may have priority when it comes to processor time?
Windows 7 does have issues with tablet services....have you disabled those? (Regardless of whether you use a tablet or not ..... the services are for a 'tablet' device rather than a real, proper, gfx tablet but because MS think everyone will be using a 'tablet' device the services are automatically started and can, and do, really screw it up for those of us that need to use an OS in a more 'professional' capacity instead of staring at 'kitty pictures' all day.
Did that turn into a rant? :biglaff:
Anyway....check out the services and see if anything 'tablet' related is running...especially this puppy...
No guarantees....and you've probably done this already but still...
Regards.
MrToM.
PS....not only has vee beat me by minutes but starts with virtually the same opening line!!!!
Sheeeeshhhhh!!! If its not one......:biglaff: