@Sam_Newton
OK. Let's see if we can make some progress here. You've had over 60 views and no replies yet. That's probably because nobody knows exactly what to suggest as an answer; "nobody" includes me. I do have some experience in diagnosing issues, however, and can use that to ask a few questions which may (no guarantee) lead to some next steps, possible even eventually to a solution.
Let's start with your description: "But, Excel (for no reason) has started crashing whenever I select a suggested formula after typing the first few letters." and note that your "for no reason" isn't quite accurate; more accurate would be "for no known reason" or "no visible reason" -- after all, there IS a reason somewhere, somehow, and that's what we're seeking.
So, putting that parenthetical aside, the rest of your sentence requires some more precise or complete descriptions.
- "has started" -- this implies that Excel was working before some point in time when this crashing started. Could you confirm that, and spell it out a bit more precisely.
- For how long was it working?
- When did it stop working?
- Has it continued to not work?
- Or is there some pattern, however sporadic, whereby sometimes it works, sometimes it doesn't?
- "whenever I select a suggested formula" --
- Are there any exceptions to "whenever"--i.e., does it ALWAYS happen when a "suggested formula" is selected
- if you just enter a formula (i.e., not a "suggested" one, but one from your own knowledge) perhaps a very basic one (e.g., =A1+B1) does it work?
- What do you mean by "suggested formula"?
- What's the source of the "suggestion"--an internal Excel prompt of some kind?
- How does the "selecting" occur (dialog window?)
- Presumably you have more than one spreadsheet or workbook. Is this happening in all of them, or just in one or two?
Going beyond those attempts at clarifying further your problem statement, some other questions:
- Was any other software on your PC updated (operating system included) just before this "crashing" commenced? Any hardware changes?
- What kind of functionality is it that you need that seems to be stressing the system so? (You allude to functionality that's not available in online browser versions, but don't specify what that is.)
- What kind of data are you working with when you experience this failure (the "crashing")?
- How large is the workbook in question?
- Do you have access to an altogether different system (e.g., a Mac, or just another Windows PC) where you could try (also with the 365 subscription) the same workbook and formulae?
And if there are other particulars you can think of that might help spell out the what-where-when-extent of the symptoms, those could offer clues as to underlying causes, form the basis for some hypotheses, and suggest steps to confirm or deny those hypotheses.
