Pat over at A place for everything has just posted a question about photographic upload problems. Apparently we are limited to how mucy we can upload, did you know that? I didn't, but went onto the blog help and found this out - go to the bottom of the page at this link:
Followed their link to Picasa and signed in using my blog identity etc.
There were all my photographs. Most are locked for access other than through my web but some aren't. How strange. Anyway, it turns out I have used up 9MB of my 1024MB storage space.
Every photograph you upload that is larger than 800 x 800px will 'cost' storage. I would recommend you crop your photographs to less than this. Mine are always cropped at 15cm x 10cm and at 72px. For me to have used some of my storage, some of mine must have been bigger when I first started posting. Now we know.