I have recently encountered a few problems with Mathematica 10 my computer. Here are the basic information about my computer. i7 4600U 2.10GHz/12G/1TB SSD/Windows 8.1 64 bit/Mathematica 10.0 for Winodws 64 bit

Problem 1: Failure to launch Mathematica. A Wolfram Mathematica 10 process occupying ~4 MB memory can be seen in Task Manager but no GUI is displayed. The possibility to encounter this problem is about 50%. It can be resolved by rebooting the computer and make another attempt.

Problem 2: The Mathematica program crashes when I type the second letter of a reserved word. It usually last 5 to 15 min until the hint appears. The possibility to encounter this problem is about 95%. I understand that I may resolve it by turning off the hint but the hint is necessary for me.