AutoCAD is changing my blocks

[Sideways Phoenix]

i have my title block split into two differant blocks one that applies to the entire sheetset and one that applies only to the individual sheet. my problem is that when i insert the block ofr the sheet and save it at some point within 24 - 48 hours the block will be replaced with an AutoCAD generated block. it looks almost like the original but the text is black. and it moves a little.
Any ideas would be gratly helpfull.
thanks in advance

[bcgatti]

When you say it is replaced with an "AutoCAD generated block" - how did you determine this (as opposed to an accidental overwriting of the block)?

Are you Xref'ing the block into your files or are you inserting it?

Is anyone else working on this file - someone who could have replaced or redefined this block?

[Sideways Phoenix]

if someone eles is replacing the blocks then they are creating blocks with names like a$1$acadle345. that is why i thought they were autocad generated blocks they are also very similar to the correct blocks there will only be one or two little changes like plot style or text size that kind of stuff.

[irneb]

Some extra info needed:

1. What ACad version and vertical
2. Is the block a dynamic block?
3. Do you use annotative scaling, if so do you save back to an older DWG version?