rectangular marquee will not deselect

The rectangular marquee tool will not deselect. I have to select some other tool (such as lasso) and then click to remove the marquee. I do not have this problem with the circle marquee. At about the same time, I started having problems with the brush size showing in the pencil and clone tools. It used to show me a preview of how large the circle would be when I switched brush sizes and moved the cusor over the image. I tried changing the cursor options in preferences which did not really help.
I am on OSX 10.4.8 running Photoshop CS2 9.0.2. and did the recent update which did not correct the problem. Here is my display info:

ATY,Rage128Pro:

Chipset Model: ATY,Rage128Pro
Type: Display
Bus: AGP
Slot: SLOT-1
VRAM (Total): 16 MB
Vendor: ATI (0x1002)
Device ID: 0x5046
Revision ID: 0x0000
ROM Revision: 113-72701-130
Displays:
E790-3:
Resolution: 1024 x 768 @ 85 Hz
Depth: 32-bit Color
Core Image: Not Supported
Main Display: Yes
Mirror: Off
Online: Yes
Quartz Extreme: Not Supported

thanks for any ideas you may have,
tammy

The rectangular marquee tool will not deselect.

Do you mean that hitting Command+D does not work?

Try deleting or re-setting your Photoshop's preferences.

Quit PS
Drag your PS preferences to the desktop
Reopen PS and test...

If you're trying to rule out Photoshop corruption or reset Default settings, FIRST try trashing:

HardDrive> User> Library> Preferences> Adobe Photoshop # Settings folder. HardDrive> User> Library> Preferences> com.adobe.Photoshop.plist file. There are several other Photoshop preferences there you may trash....

Problem solved! Trashing the plist file did not work, but one of the other files I trashed did the trick. Of course I didn't do it systematically so i can't say which one exactly (probably Adobe Photoshop CS2 Prefs.psp). I am not as comfortable in OSX removing things from the system. Sometimes I still long for the good ol days of System 9 when I knew where everything was and what it was for...
thx,
Tammy