GameRenderer Graph Value Exceeding reasonable ie 99% causing lag/crashes

The Game renderer Graph Value(shift + f3) root[0] has gone exceptionally high

For it to stay at a reasonable level like 80% as far as I know and for me not to crash

The biggest Problem is that I can't take a screen shot because when ever I get to around 90% or higher when I take a screen shot I crash from memory loss.

May I add these Are my Specs

Core i5
4 core processor
8G of ram Total
1 G dedicated to Minecraft

Also im really confused because when I crash its not like I don't have enough ram because it will be using only around 30% of what can be used total but it still crashes im not sure what the problem is. If this could be fixed that would be great also if anybody has any ideas on ways to fix this please comment them because I might just be doing something really stupid but I don't think so.

Also random thing it as far as I've noticed It effects from 1.7.2 and up but it wouldn't let me select 1.7.2 though.

Steps to Reproduce:
I've Just been playing and im not sure what the problem is it just started happening on all servers I've played on.