Excel pivot prompting database password - none needed

Hi, am working remotely from home and have started getting this error.
When refreshing a pivot table, I'm being prompted for a database password when there isn't one needed. This isn't happening consistently to all pivots either.
The first was a file pivoting from an Access query off a sql table (don't ask the logic behind it!) so we checked all permissions for me - fine. Colleague made new file, created connection, ran it then emailed to me and I get prompted for password.
Second time yesterday is a pivot linked to an Access table. No SQL permissions needed. Ironically had been in file 20 seconds before, refreshed it fine then closed without saving. Went back in and was prompted, can't do anything.
Have since created new database, imported the one table in, still can't connect to it. Is there an Excel setting that I may have overlooked? Nothing I link to is password protected.
Thanks in advance for any help, am getting desperate as IT haven't a clue.

I should have made it clear, I can access the databases perfectly fine and run all the queries. It's just for some reason I can not now pivot off them which is essential in my job. I can see all the raw data and access it easily, but I'm trying to pivot off the source and have done successfully for years, without having to paste it into the spreadsheet and go from there. Our tables contain sometimes a couple of hundred thousand rows of data, hence can't copy them into excel.