3D Printer doing random moves

Hello All,

I am new to 3D printing, I have built my printer using a kit of electronics and designed and built the frame out of aluminum.
Recently I updated my Marlin to version 1.0.1. Is this the latest version?
I have just installed a additional extruder to print 2 material prints.
What my problem is and it started occurring on prints sometimes before is that all of a sudden during a perimeter run or infill the printer will suddenly move to the extent of the Y minimum or the X maximum, then return to the print leaving the filament extruded out of the print and missing the next piece of extrude.
Another issue is that the printer will seem to get ahead of itself and all of a sudden cut corners, an example being that if the perimeter was a circle it would draw through a segment then continue.
I left the printer the other day to see the result and see if the effect only happend at the begining of the print, then some random characters appeared on the bottom of my display area of the graphics LCD, and stopped printing.
Occasionally on my previous Marlin V 1.0.0 The print stopped with the words Wait for User on the bottom of the screen, after waiting nothing happened and if then you press the encoder button the head would drive down to Z 0 and stop.
Any ideas and help would be appreciated. Its great when 3d Printing works but frustrating when it doesn't. If you need any additional info about my printer let me know.
Cheers

What slicer? USB or SD?

G'day Mjolinor,
Slicer several versions i've tried seem to have similar effects, thou I did think that it was the slic3r program which was making bad G-code, i am not 100% convinced now that it is after trying the latest version, and the experimental version.
I was using slic3r version 1.0.0RC2, then switched to version 1.1.7.
The same sort of things happened with the latest version i also tried version 1.2.4b experimental thou it didn't provide my requirement to import multi part stl files.
I am using a SD card, thou I switched to this as just after I built my machine the seemed to be bugs when printing through the USB.
I tried disconnecting my cooling fans, to try if there was an issue with noise from them, no luck. One print I am using as a test to see if the problem is fixed plays random moves on the first layer, and its not a complicated print.
I am using a Ramps 1.4 board with a Arduino Mega 2560.
Cheers

Use a different slicer. I gave up with slic3r after at least a month of trying, it is brain damaged and does really stupid things for no reason.

Try Cura. You can always go back to slic3r once you prove that is the problem and try to fix it then.

Thanks for the info. I did actually download Cura, when I was suspecting that the Slic3r was the problem, but was a bit scared off with the different interface, and as I thought I was getting the hang of the settings to use in Slic3r as the default ones never really worked that well. I'll give it a better go now.
Cheers

Can you provide me a link to a tutorial if you can of the ability of Cura to combine two stl files, into a amf, to do a two color print? Or do you have to have a amf file to import?