Can't add new rules, can't access page to manage rules

I started adding a lot of rules to my account on Outlook.com. The rules I have set up are working fine. But now when trying to add any new rules it's failing and when I go to Settings>Manage Rules I go to a blank page with an error message.

Details:

Adding new rule. Right-click on a message>Create Rule. Dialog comes up, I'm able to fill in all fields and click Apply/Okay:

    - I get a message at the top of the screen stating "Sorry, Outlook.com wasn’t able to complete this request." at some point while filling in the fields.

    - When clicking on Apply/Okay I then get red text at the bottom of the dialog stating "Unable to cast object of type ‘Microsoft.Msn.Hotmail.FDCommon.Data.Xfs.XfsException’ to type ‘Microsoft.Msn.Hotmail.InboundMail.MailRules’."

Going to Settings>Manage Rules:

    - I get to the settings page, but none of my rules (The ones that still function normally when receiving mails) are present and there's a message at the top of the screen stating "Something happened at our end. Please refresh your browser or close it and sign in again."

   - When trying to create a new rule within this page, I get the same error as when on the main page stating "Unable to cast object of type ‘Microsoft.Msn.Hotmail.FDCommon.Data.Xfs.XfsException’ to type ‘Microsoft.Msn.Hotmail.InboundMail.MailRules’."

Have I hit some limit on the amount of rules Outlook is able to process? I have created a lot of them, over a page of rules, all of them just moving stuff into folders based on sender name.

Is there a way to clear my rules so I can start again?

Have tried this on the following operating systems and browsers: Windows 7 Professional, OSX 10.11.2, Safari 9.0.2, Internet Explorer 9, Firefox 43.0.1 (and at least one earlier version), adblockers and virus/malware checkers all disabled at some point in case that was an issue.

Also, tried the above steps on my girlfriend's account (which has no rules set up yet) and it works fine. Can create new rules, and access the manage rules page fine.

What can I do?

If I can't access the Mange Rules page to delete some rules that might be causing this, then I need someone from Outlook.com support to do something right?

Cheers.