I would suggest you to clear the cache and cookies stored in your browser and temporarily disable your antivirus and other third party protection software's.
After completion of these steps restart your computer and go to https://account.live.com and enter your Windows Live ID (associated with Microsoft Office Live Workspace account) and password and click on Sign in. You will be inside your Account Management page.
Remain signed in to your account and open a new tab and access your Microsoft Office Live Workspace account.
In case, if you still face any problem then provide us following details:
1. Operating system and browser version installed?
2. How often you face this issue?
3. Have you made any changes to your Microsoft Office Live Workspace sign in details (like change in ID or password)?
4. Is this issue specific to opening/accessing one specific document or with all the documents?
Thanks
Sunil Raina
Microsoft Support Engineer