Modules/Payments: Modules not 'clickable' !?! What now?

After loggin in as admin, clicking Modules/Payments, a nummer of payment modules is shown.

Normally, these should be 'clickable', after which you can Install/Edit the modules and enable them.

However, when clicking anywhere, they are 'dead', nothing happens.

A number of modules seem to have disappeared as well, No Paypal anymore, which I want to enable now. Even the only payment module active now (the Dutch "Incasso") is not visible, but works.

Has anyone a clue what happened and how to solve this issue?

May be I have to rephrase above a little. Clicking may not be 'dead', but the right-hand side box does not appear. The arrows are pointing to the rim of my monitor.

Same applies to Invoice module.

Modules for Shipping appear as normal with the gray right-hand side box.