I have a Dell Inspiron 8100 Laptop that had a memory read/write error.

The computer would get so far through the boot up sequence then freeze.

I was told it was a faulty memory card and had it replaced.

The computer now boots up but the screen freezes randomly - usually when I operate an application that uses some memory. If I boot up and do nothing the computer seems to run ok.

I was charged $180 to replace a memory module (256MB single module instead of 2x128MB) which I later found to be day light robbery.

Is this likely to be a suspect memory module or could this be the memory slot?

The new memory module was inserted into slot B but Dell recommends a single module to be put in slot A. When I swapped the memory into slot A, the computer would not boot up.

How can one combat companies that advertise as reputable service outfits but seemingly take advantage of those not up to speed in technical matters?

Any advice?