Jalal,
You are on the low end of memory at 2Gb; 4Gb min, is preferred. I doubt this is causing the problem at hand.
It could be one or two columns, not all 4 that are causing the problem. Are they exactly alike? If not perhaps there is a setting that is causing the problem.
Did you try replacing them?
Are these columns made with the column tool, Custom Profile, sloped or a library part ?
If replacing them doesn't work, post a screen shot of the columns' settings.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"