ticking screen error

Put the summary of the bug you're having here

What I expected to happen was...:
usually it logs me on to the nexus but it crashed thegame and gave me a ticking screen error.
i have tried reloading my minecraft and even redownloading the game
but still nothing

What actually happened was...:
above

Steps to Reproduce:
1. go on to the nexus on 1.7.9
2. it crashes
3. ...