After NOT automatically updating users for the past year or two, Panda is finally arranging a "controlled upgrade" from versions 16.x.x to version 18.0.1 [Presumably this also updates 17.x ???]
The following was copied/pasted from http://support.pandasecurity.com/forum/viewtopic.php?f=83&t=6313&sid=279ac3f7de63ccc03261069cdc665e12
[On M]onday, May 15th we will publish a controlled upgrade for the "old" Panda Free Antivirus versions 16.x.x to the new version 18.0.1 based in Panda Zone.
If anybody experience any problem related to the product interface, please install .NET Framework 4.0