This is my first time having such trouble, but I'm only a casual user.
I have a base raster layer of the school I work for and I've been adding vector shapefiles on top of that in separate installments. I made a map of trails and the shapefiles from that show up on the view and layer list. I then add a vector layer of flower beds and as soon as I do that the trails disappear from the main view. The CRS is the same, the Trails are still listed in the Layers and I've brought them to the top of the layer list. I can select them from the attribute table but they still don't show up. Removing the flower beds layer doesn't fix the issue, I need to start a new project to get the Trail layer to show again.
The flower bed layer doesn't cause the topography layer to disappear which is another line shapefile I've reused from another project. I've also added another line layer and point layer on top of the flower beds and they don't disappear.
I've tried this in QGIS Valmiera and Brighton on a Windows XP and Ubuntu machine respectively and the issue is the same.
Any ideas what's going on?