Could anyone help me clarify the problem of available Ram in Photoshop? I could not find a similar problem in the archives.I'm fairly new here.

The problem is this: From time to time I encounter a memory shortage even
though I regularly purge the cache.
My Windows PC system works on 3Gbytes of Ram displayed as such in the set up.

but when the CS2 version is open , on its own, the preferences dialogue box reads
"1.749Gb is available ( out of which the ideal range is...)" Is that % Ok?

and what's more the CS3 version only provides 1.472

Thanks in anticipation

Within Windows is a startup setting referred to as the 3GB switch. If you proceed with caution (if you mess it up, Windows will not start), engaging this option should allow you to assign more RAM to Photoshop.

Be sure that everything is spelled correctly and syntax is correct.

See:

http://forums.dpreview.com/forums/read.asp?forum=1004&message=23713215
http://forums.dpreview.com/forums/read.asp?forum=1006&message=26670489
http://www.adobeforums.com/webx?128@@.3bc3af59

I'd come across that issue, but thought that having less than 3Gb installed I didn't have to bother about this.
Thanks for the links. I may have to reconsider.

As I understand it /3GB will unleash some RAM resources to applications, but read the fine print very carefully to avoid self-inflicted hosing.

Good luck... Keep us posted on further discoveries.