I have a program installed in my computer that I and other members of my company need to use while we are at a trade show. Since the program is installed under my username how can I lock other areas of my computer so that if I leave the booth for a few moments my colleagues don't go snooping into other folders in my PC? Is there a way of "freezing" the PC to only work on the window it is on, and not to open anything else?

Or do I need to reinstall the program under a restricted user and run it from there?

Create a second user account on the system (restricted user) and allow access the program from there. You shouldn't have to reinstall the program - it should be available from the second account. If the program needs admin priveledges, right click the program, choose "run as" and enter the administrator username & password.

You can also password protect your user account along with associated files & folders. In Control panel click user accounts. From there you can create new accounts and password protect exisitng accounts along with making files & folders private.

Alternatively, you can do this to make folders private where they can't be accessed from other accounts:
How to Set the My Documents Folder to Private
To set the My Documents folder to Private:
1. On the Start menu, right-click My Documents, and then click Properties.
2. Click the Sharing tab, and then click to select the Make this folder private so that only I have access to it check box.
3. Click Apply, and then click OK.

Please note that in order to have the ability to make folders private the disk must be using the NTFS file system. Also, "the option to make folders private is only available for folders included in your user profile. Folders in your user profile include My Documents and its subfolders, Desktop, Start Menu, Cookies, and Favorites".

One last thing - make sure to set a password for the Administrator account. This is often overlooked. If you don't password protect it you're leaving the backdoor wide open, especially if you're going to be connected to a shared or wifi Internet connection at the show. Oh, make sure to disable all file & folder sharing too

Also, "the option to make folders private is only available for folders included in your user profile.

Not exactly true. You have the option of just changing the ACLs (access control list) on any folder you don't want them to see. Create a non-administrator account as Alan suggested and disable simple file sharing. There should be a new tab called "Security" when you right click a particular folder/file and go into its properties. Remove everyone besides Administrators and yourself from the access list.

For encrypting your folders, you are only allowed to encrypt your personal profile under c:\documents and settings\username
Encrypting however isn't really needed in your scenario.

//krunk (^_^x)