Sorry, make that 199/200 after that brick in the trophy room. The only detectors that go off now in hogwarts is the red brick arrow in the staircase room (got it) and the arrow pointing to an area in the northwest area of the restricted section (walkthrough says it is a glitch, or is it?). Any other arrows I find I can update on this forum topic, so if you can tell me if the arrows ar glitches or real once I find and try to figure out which they are on my own. (basically, I find, try to figure out, update forum and ask you what you think.) Hopefully, it will be found soon because thisngame is starting to make me mad with all of it's glitches.
The red brick indicator in the stairway is an error, as is the house crest indicator in the restricted section (it looks like the gold brick indicator, but it's not). The last gold brick for me was the one over the pot of water in Hagrid's garden, even though I already got it before.
Want a second opinion before disputing that moderation? Go to Hellhole: http://www.gamefaqs.com/boards/573081-hellhole