HP 550 updated and since then I can't do anything with the cursor. The log in screen was static as usual, and allowed me to enter my password, then the desktop loads and flickers every second between plain black screen, desktop, then desktop with my icons. The cursor will move around the screen but I cannot select the window at the bottom left to select any programmes or anything. The cursor is the blue circle not the arrow. I've turned it off twice and same result each time. What can I do? I found a few similar problems asking for windows update to be run and anti-virus to be removed, but I can't do that without the cursor being functional. PC is exactly a year old, but was completely unused for 10 of those months as I was abroad and using my Mac. Any suggestions?