slow upgrading attachments to file system 423

[r5mjh]

hi all just a quicky when i am upgrading from 3.7 to 4.2.3 i keep having to refresh the browser while its coping attachments to the file system, is there a reason for this does its corrupt the file its writing or rewrite when i refresh, this so annoying also i have to refresh at 3 other points after as it halts again and needs to be refreshed

any help greatly received is there a way of stopping it crashing?

thx mick