Try using "Always Fresh" to clean your changes or start over. You might also want to try using Slax on an ext2 formatted drive, as it will be less prone to corruption like on FAT32. Also, have you tried using a swap file or swapspace yet?--this might help. If these don't solve your problem, try using memtest to look at your RAM, or look into your drive's health with a system that includes Gnome Disk Utility, like Mint or Ubuntu.
Hope this helps answer your question--good luck. :)
Slows down after some time, could be a RAM issue. Are you running out? I do not know your Boot options but if it is from a CD and you open Applications that are Heavy and have less RAM then this may be the Problem.Install to USB with a ext2 filesystem. Works for me for a long time now