HELP| Will updating you ML stop the OS X Lion 10.7.5 Freezing?

Hello

I need some help. I have the mid 2011 iMac

Processor 2.7 GHz Intel Core i5

Memory 4 GB 1333 MHz DDR3

Graphics AMD Radeon HD 6770M 512 MB

Software Mac OS X Lion 10.7.5 (11G63)

Ever since i updated to the 10.7.5 my Mac has been freezing when i launch my computer and has caused me to do a full socket power turn off or hold the launch button to turn off then reboot the mac.

Will updating to ML fix this issue?

I have already installed the The JRE (Java runtime environment) thinking that may have been the issue but it was not. I do not want to upgrade to ML because of th bugs etc that have been occuring but if needs be then i guess will have too. Please could you share your opinion on this situation.

(BTW i have all my important files backed up onto an external hard drive )

Thank you