Do not re-install.
Try deleting your Previews folder. Lightroom will rebuild previews as you use it in future.
Lightroom must be closed- Find your previews folder- It will be in the same folder as your catalog. The folder will be named similar to "YourCatalogName PREVIEWS.LRDATA"
Delete this folder, and nothing else.
***CAUTION: Do NOT delete the ..LRCAT catalog file (this has ALL your data.)
Restart Lightroom- Hopefully the problem is solved.
To find you Catalog & Previews location-
Menu > Edit > Catalog Settings > General Tab > [Show]