AutoCAD 2010: Dissapearing Lines when Alterting scales in Viewports + Model Space

[iPhobos]

I have 2010 and for some reason today cannot alter the scale of my drawings...model space is set for 1:1, paper space displays viewports at 1/8", but once I shift to 1/4" most lines [not just annotative objects/text] disappear, however are still there because I can still highlight them...same thing happens when I test out changing model space to 1/4" scale, most lines inexplicably disappear. I drew everything in a 1:1 void from scratch/clean new files. Googled the help forums, and only find people with lineweight issues [lol] etc, I've already fuddled with all the linetype scaling settings [ltscale, msltscale, psltscale, celtscape], so am at a loss. Any help would be much appreciated!

[RobDraw]

Can you post a file please?

[iPhobos]

Can you post a file please?

 

Sure, just tried uploading, however apparently file size limit on this site is 1MB...will have to reduce file [1.2MB] later on when I can switch to bootcamped pc partition.