If you upgrade to Maverick, you do not need to adjust RIPCache any more. There Ghostscript manages the memory automatically. On Maverick (or newer) run
cupsctl RIPCache=auto
to cancel any former memory setting.
In general upgrading to a newer Ubuntu will always help, as we have fixed a lot of resources problems with Ghostscript and other print filters.
Simply try a higher value, for example
cupsctl RIPCache=512m
If you upgrade to Maverick, you do not need to adjust RIPCache any more. There Ghostscript manages the memory automatically. On Maverick (or newer) run
cupsctl RIPCache=auto
to cancel any former memory setting.
In general upgrading to a newer Ubuntu will always help, as we have fixed a lot of resources problems with Ghostscript and other print filters.
For further discussion, join bug #668800.