Whether a text document or spreadsheet and I want to save as other file (.xls, .doc) Libre will freeze and I have to close the program and loose EVERYTHING I was working on. I use a LOT of spreadsheets in my work
Which version do you use?
Try using ODF and multiple problems will not appear. Use Microsoft file types only if you need to exchange files with other users. Are you maybe using some kind of network file storage? If yes, then save to local disk.