A serious problem has occurred

When using Cubase Le 4 I am receiving an error that reads;

A serious problem has occurred: Please try to save your project under another name and then restart Cubase LE 4.exe. If this problem persists please contact Steinberg Technical Support with a description of what you do to create this problem, and the created file C:\Program Files\Steinberg\Cubase LE 4\Cubase LE 4.LOG.
Clike ‘OK’ to be informed about further occurrences of serious problems, or ‘Cancel’ to suppress these warning in case of cascading warning.

The error tends to happen when I begin to use any VST effects. I am unable to locate the specified Cubase LE 4.LOG file.
I am not using any external devices when receiving the error. I have done a full reinstall but still getting this error.

Platform: PC
OS: Windows Vista 32 SP2
CPU/Computer model: Intel Core 2 Duo
RAM (GB): 3

Any help would be greatly appreciated
Kind regards

Which VST effects? Native Cubase effects or 3rd party?

Possibly a RAM limit issue?