Left Navigation Bar Disappears

Dear experts

We are using CRM 5.0 and PCUI applications integrated within the Portal. When we click on a hyperlink to open another type of document, the left navigation bar disappears. Do you know how to solve that?

Example 1: Create a service order and save. Go to document flow tab create a new case, save. click on the case hyperlink. The case opens but the left navigation bar disappears.

Example 2: If you are individually viewing an activity (e.g. selected via the activity management search), that belongs to a case, then navigate to it's parent case via the cases tab and selecting the case's ID, the shorcut quick links in the navigation sidebar disappear.

Thanks in advance for your help

Best regards

Stephanie