If you change the ISP or your router, you must reset the Slingbox for it to acquire a new IP address and be able to be reached over the Internet.
Since you also mentioned that you were getting a cross sign instead of the regular cursor using Internet Explorer, you can try to reset the Internet Explorer settings and try again. Feel free to access this links to get the instructions.
How to reset your Slingbox
Resetting the Watch on Slingbox.com plugins for Internet Explorer (ActiveX) and Firefox
Christina: Is there a good reason why you have not responded to my response to YOUR email? Let me try this a third time: When attempting to configure my Pro-HD through the desktop software, the software simply locks with a white box. To make matters worse, I cannot configure my Pro-HD online because your website "Country Selection" screen does not work. None of the links will operate. So, your software with not allow me to configure the Pro-HD and your website "Country Selection" page does not work. Is it asking too much for you people to get your act together. The amount of money I have spent (wasted) is substantial. Further, I have tried Internet Explorer, FireFox, and Chrome and all fail to get me past the "Country Selection" page.
Nothing beats excellent customer service. In this case, Christina must have missed the memo. I am still waiting for some type of response from SlingMedia. Anyway, perhaps anyone can help. I have the Slingbox PRO-HD and both the mobile versions for the iPhone and iPad. Because Comcast transitioned their programming to all digital, I am not longer able to use the Slingbox PRO-HD and the mobile software. Now, how am I expected to configure this hardware to operate properly?