My previous question on this was closed, but I am posting it again as the solution which my son eventually found may assist other users of the forum, or someone may be able to tweak the solution to improve the performance.
Having installed Kubuntu 12.04.01 from a live USB onto my desktop, I wanted to do the same on my laptop, an Acer Aspire 1362 Laptop, which has 256MB RAM (actually 512 "on the box", but a good deal can be borrowed by the graphics!). I found Kubuntu wouldn't run on so little memory but downloaded: Lubuntu-12.04-alternate-i386.iso, which I understood was light enough to go.
The laptop has one internal 40GB Toshiba hard drive divided into 3 partitions: C,19GB with Windows XP, Windows program files and some data, D, 19GB mostly data, and a small 2GB partition with some Acer software, which XP can't normally “see”. I transferred most of the contents of D to a memory stick, leaving 16GB free for Lubuntu. I did not want to dump XP yet, though it is painfully slow. I installed Lubuntu from then USB stick, accepting the default answers to most of the questions. The D: partition was further partitioned into a 500MB boot partition, 10GB for Linux, 2GB Swap and 6GB for data shareable between Linux and Windows.
I had no error messages during installation, rebooted, was offered the choice of Ubuntu or XP, and selected the former. After a few minutes, I get a dark blue screen announcing Lubuntu with five dots underneath which lighten in turn. Eventually the lights stopped, and whatever I try the screen remains blank apart from “Lubuntu”
I tried several solutions suggested on the forum for “identical” questions but without success.