Flickering while booting Ubuntu 14.04 LTS

This problem is there for the past 15 days.

My Laptop is HP Probook 4520s, with i3 processor and Intel HD Graphics.

I turn it on, the purple Ubuntu appears with constant flickering. There is no progress from this screen.
So, i have to shut it down by hard pressing the POWER Button.

I again turn it on, but this time i get a another surprise.
After selecting the option Ubuntu from the boot menu which appears (showing the option to select Advanced options for ubuntu)
i get a black screen with the following pattern
[[19~^[[19~^...........
This keeps on appearing until i press enter.

After that the above pattern appears in a smaller font, followed by 13.571... Bluetooth hci0 tx timeout.

Then i get the logon screen, i type my credentials and i am in.
But this i have to follow every time i try to open Ubuntu 14.04.
Hope someone provides a solution to me. Cheers!!!