I've seen other, similar questions and I think my issue relates to more than just a dirty trackpad.
- Mouse pointer moves around erratically.
- Very hard to control the the pointer.
- Sudden, random clicks of this or that on the screen.
- Hard to click on anything with any confidence. Double-clicking is nearly impossible.
- Right-clicks also happen randomly.
- Pointer jumps around even when I am sure I haven't accidentally touched the trackpad.
- The equivalent of pressing Fn + F11 happens very frequently.
- Dragging windows around is a pain
From the May-be-Unrelated Department
- System performance is generally slow (but when three such memory hogs as Firefox, Chrome and Eclipse are running with just 4 GB RAM, this isn't entirely unexpected).
- Many apps often hang for no apparent reason. Frequent offenders: LibreOffice 4.x, VLC, Preview, Google Drive, uTorrent
- First saw this issue about 1.5-2 months ago.
- Problem comes and goes. When it comes, usually lasts for a day or two. Most recent one started last night.
Investigations/Efforts So Far
Heat issues (inflated/bulging battery)
I investigated whether this might be due to heat (inflated/bulging battery under trackpad), but I've noticed this problem even when the MBP wasn't hot. For example, I shut down the laptop last night and when I booted up this morning (when it was guaranteed cold), the problem was still there.
The first time this occurred I suspected bit might be due to a small liquid spill on the trackpad. I cleaned as best I could and it went away. But the problem has recurred since without having spilled anything on the trackpad. I haven't opened the MBP, but otherwise have thoroughly cleaned the trackpad.
Safe Mode, Resetting System Management Controller etc.
I've tried cleaning the trackpad from above (i.e., without opening up the laptop), but can't be certain whether it helped solve the issue or not.
I've tried booting in Safe Mode, but had same issues.
I've tried resetting the System Management Controller (SMC), but since there's no feedback, can't say whether I succeeded or not. Problems obviously still persist.
I downloaded, installed and ran the free version of Avast anti-virus — it found a Windows virus in one file. That file has been around for a while (plus it's a Windows virus), so I don't think that's the cause of the problem.
- MBP 13 (Late 2011 model bought in Jan 2012)
- OS X 10.9.3
- All the latest updates installed