That is rather odd. Let's try plugging the unit directly to your PC and try and access the web interface that way. If the unit has a static IP address set you will need to set your PC's ethernet card to a similar IP address to communicate with the Linkstation. If it does not then we can reset the LinkStation and have both your PC and your Linkstation on dhcp so they can both see each other. You can use the Nas Navi to find the IP address in this case. Here is the reset process.
Please switch the unit to off and wait until the lights are off.
Hold the function button for 10 seconds while it is still off.
While still holding the function button after 10 seconds please flip the switch to on.
Once the function light begins to blink release the function button and press it again for one second.
Wait until the power light is solid and this will restore your unit.
This process will not delete any data and will only restore the admin password and set the IP address back to DHCP.