Vexana111la This is certainly not a common issue, and it sounds more like a leftover process is running or (more likely) that your security software is flagging some Gallery-related process and blocking it after the first use. Reinstalling the game would restore any quarantined files and replace blocked ones with fresh copies.
Since the first possibility is easier to test though, does this happen if you restart your computer after accessing the Gallery? I mean a real restart, not just shutdown/reboot.
Aside from that, what antivirus do you use, and does it list any recent actions that might be EA- or Sims 4-related? Does it help to disable the AV before playing? As long as you didn't do anything else at the same time, your computer would be safe, and you could reenable it after the test.
