discuss.answer
FYI, I've figured it out.
I deleted the contents of /core/cache reloaded the /manager page and it worked. I do remember that the machine froze will in the middle of working so my guess MODx didn't finish saving.
What do you mean by deleting the contents of cache? All the subfolders? Is that safe?
Yes, you can safely delete all files, folders, and subfolders in the core/cache/ directory. MODX will create fresh versions of them. If you have a corrupted cache file, it's sometimes the only way to fix it.