First time poster and a new user working my way through the tutorial:
When I add an emitter to staging, I get small black box over the emitter that's (generally) the size of my mouse pointer. I'm not using any special cursors or anything.
When I try to create a curved path, the handles are difficult to interact with because they may not always be visible. If I drag an emitter, I'll see the cursor flash in and out in what looks to me to be PI not repainting the section of the stage where the mouse pointer resides. If I do not use hardware acceleration, I don't get the artifacts but the emitter looks distorted.
Motion blur is not on and if I have Show Particles disabled, adding the emitter doesn't do anything (on screen) until another emitter is added. At that point, emitter #1 becomes visible and the newly added emitter is not shown.
I don't have any issues with playing the animation or in the preview window. My issues are exclusive to interaction with the staging window.
If it's worth pursuing, I can install GLIntercept or some other OpenGL diagnostic if it will aid in resolution.
I'm perplexed as to my next steps because my drivers are signed as being WHQL-certified and, more importantly, disabling hardware acceleration is kinda like riding the bus when you bought a Ferrari. (Ok, it's an Nvidia 8800GT. Replace Ferrari with Dodge Neon.)
I set my mode to Add, left clicked (and hold) in the staging window. Then I moved the mouse with the button still down half the way up and across the staging window. When I released the mouse button, the emitter icon and preview showed perfectly.
Convinced it had something to do with my mouse, I opened Control Panel (Start > Settings > Control Panel). I found I had "mouse trails" on with a trail length at the absolute minimum. I don't like mouse trails, don't need them, and when I turned them off, PI worked perfectly.
To summarize...for me: Mouse trails = black block artifact when interacting with emitters and paths in the staging window.
Hmmm...my post included information specific to my config (operating system, hardware, drivers, etc) but it didn't appear in my post. I don't know if that was trimmed by the forum software or if it was by a moderator...? If a moderator, why remove info that might help in troubleshooting?