It's a DNS issue. I could access the site from one PC but not another. The fix for me was to flush the DNS on the local PC. To do this:
- Close the browser
- In Windows click the Start button
- Click Run
- Type CMD into the Run window and click OK
- In the black command window type ipconfig /flushdns and hit Enter on the keyboard
- Then type ipconfig /registerdns and hit Enter on the keyboard
- Open the browser and try accessing Istock
EDIT: Correction, ipconfig was missing an "i"