Without proper system information nobody can tell. You info is at best vague. You will have to provide the full details like screen resolution, graphics hardware, what mouse, input settings, awhether you use alternate input devices like tablets or a touch screen and a gigazillion other things. Also provide the relevant details about OpenGL and input settings from the C4D prefs.
Thank you Mylenium. I wasn't sure what details to provide, but I'll do my best to cover everything you asked about.
As far as the computer, my PC is running Windows 8.1 Pro (64-bit). The hardware is as follows:
Processor: AMD FX8120 (8-core, 3.10GHz)
Graphics: NVIDIA GeForce GTX550 Ti
Input Device: Wacom Intuos3 Tablet (using provided mouse, not pen while using C4D)
Memory: 16 GB usable (have 32 installed but haven't spent the time to figure out how to get it all to work with Windows 8)
Screen Resolution: on Monitor #1 (HDMI) and Monitor #2 (Analog) it is set to the recommended 1920 x 1080
I managed to be able to get in to the Preferences within C4d somehow and these are the things I thought might be pertinent:
OpenGL settings: it IS turned ON (Linear, Anti-Alias = 4, Max transparency = 2, Max Lights = 8, Max Shadows = 2, and Use Shader Cache is checked)
Memory settings: the cache is defaulted to the C drive. I set my cache in AE to the B drive, which I would prefer but I C4d won't let me change this at the moment)
Input Devices: PSR Cursor = False, Tool Cursor = true, Mouse Move Activation = True, Graphics Tablet = False, Hi-Res Tablet = True, Open Commander Dialog on Mouse Position = True
I'm thinking the fact that the Graphics tablet is unchecked in C4d might be the issue? I can try to change it with the trick I originally mentioned, but let me know if there is anything else you see that you think might help. Did I miss anything? I really appreciate it! Thank you.