IP address problems...

I was recently in a field school in Poland and brought my HP mini with me.  While there, we had to have some Polish IT guys come and work with each laptop individually to set them up to receive the wireless where we were staying.
I am assuming that they changed the IP address on my mini.

Now, back in the states, my mini cannot connect to any wireless. It shows that it there is a wireless connection, it even says connected, but it doesnt really connect as the internet wont work. 

I know this is an IP address problem because the IP address is different on my HP mini than on my Sony Vaio.  I did try to reset the IP address, but there is something about the internet options that is not allowing this change.

I actually just had a skilled computer friend over who tried to fix it for two hours and was unable to.  He said that he doesnt know exactly what is causing the problem, but that for some reason we are unable to reset the IP address. 

If anyone wants to try and get to the bottom of this with me, I'd be very very grateful!!

I would make sure IP Address is set to Dynamic and not Static. If it is set to Dynamic and still not working with correct credentials you can check your HOSTS file to make sure that there isnt something there that is redirecting traffic. You can also perform an IPCONFIG/FLUSHDNS at the command prompt ...This is assuming your Mini is running Windows OS.

1.  Wireless Adapter Configuration.  This should only be an issue if you're unable to establish a wireless connection to wireless access point.  Must match the configuration set at the wireless access point.  This could include:
     a.  Wireless mode (802.11a, 802.11b, 802.11g, 802.11n)
     b.  Channel (Frequency band - 1 through 11 in USA).
     c.  Security Set Identifier (SSID - aka Network Name)
     d.  Security method (none, WEP, WPA, WPA2)
     e.  Encryption key length and key value or pass phrase

2.  Ping.  Determine what you can "ping" successfully when "connected".  From Command Prompt window:
     a.  ping 127.0.0.1
     b.  ping <host_computer_IP>
     c.  ping <local_gateway_IP>
     d.  ping <DNS_server_IP>
     e.  ping <69.72.169.241>
     f.  ping www.computerhope.com

Report the results of each ping.

To get a Command Prompt window (within Windows XP):
     a. Start
     b.  Run
     c.  type "cmd" without quotes, select OK

3.  TCP/IP Configuration.  Bring up a command prompt window, enter the following commands, and "post" the output to this thread:
     a.  ipconfig /all
     b.  route print

The following syntax will redirect command output to a text file (if that helps):
     c.  ipconfig /all > c:\ipconfig.txt
     d.  route print > c:\route.txt

4.  Internet Connection.  Check browser configurations (Internet Explorer, Mozilla Firefox) to ensure they're not set to use "nonexistent" proxy server.  Normally you wouldn't use proxy server.