MacBook Pro early 2011 Has blue apple logo

Hello

for the past week I have had troubles with my MacBook Pro early 2011,

On start up the normally grey apple logo and progress bar appears blue on the usual grey/white screen. I have reset the pram, smc, started in safe mode, tried repair permissions, disk repair ect ect..

even if I load in recovery mode it the drive shows up blue, and when clicked it goes no further after loading. Occasionally it will start up normally and it functions as usual.. For a while. it begins to struggle when having a few apps open. task manager shows me apps aren't responding. I click restart and it partially shuts down. then have to hold the off button to force it off.. The blue logo and progress bar are back.

I have installed a brand new battery and hard drive around 5 weeks ago, as my hdd was corrupted and battery was shagged. Also upgraded the memory to 16gb. Everything was running good as gold since then until now..

Has anyone else expirienced this? Its doing my head in and I need my computer desperately!!

Would appreciate your help/advice

cheers