Thanks for joining us here in the community! We are thrilled to have you with us.
My first recommendation would be to clear out the cache and cookies from the browsers. I have found this can help quite a bit on several different behaviors, so it's always a good troubleshooting step to start with. I would also double check out your task/activity manager to make sure nothing else is taking up all the processing power on your machine.
With that in mind, if you have already taken these first troubleshooting steps and still cannot login, you will want to reach out to our support team directly so that we can assist right away! You can reach out via chat widget described here, or via email at Support@shipstation.com.