I'm having a real head-scratching moment here...

See attached screenshot. The pop-up dialog box said that "Sims3Launcher has stopped working"... but I can still click on the Launcher itself!

Now, I started the launcher because I want to install a .sims3pack file.

Do you think it's safe to ignore the pop-up and just continue?

Or do you think this will damage my TS3 userfiles?

I get glitchy popups too and I just ignore them (by selecting "No" since clicking yes will only make it popup again). Although I get a different message: http://puu.sh/f6r5n/fac699ac13.jpg

If you are overly concerned then you should back up your save files by creating a folder somewhere and naming it something easy like "Sims 3 Backups" and copy all of the files in your "Saves" folder (or, at least the ones you want to keep) and paste them into your new "Sims 3 Backups" folder. You can also do this for your .package and .sims3pack files. When that comes up see what happens when you click the x. If it closes the program then I would move the window aside and see if you can continue your work even though you have that popup in the background.

If all else fails then try to stick to .package files although I can see that your problem is that you're trying to get a lot which, if I'm not mistaken, only come in .sims3pack

Updates? c:

After some checking, I found out that it was due to a corrupt sims3pack. The sims3pack that I was trying to install, I had edited its contents, and possibly had repacked it wrongly.

I replaced the sims3pack, and it no longer crashed.

Anyways, I did choose to end the Launcher, backed up the TS3 folder, and tried 'barging through' the error message; didn't work. When the Launcher started doing the actual install, another error popped up, the Launcher stuck, and there was no way to continue.

Ah, I see. Different error different problem, durr. Silly me. I'm glad you were able to find the problem at least!

No, this one's a totally new sims3pack of a newly-released Lot. It got 'infected' by one if the infamous bad CCs. I had tried to edit it manually, but managed to corrupt it instead.

Later I just edit it with CUSTARD, and all's well.

Go search the internet for "ArezzoBathroomCounterRight", and you'll understand

The counter even though bad, was nothing compared to the "creepy doll", that damn thing copied (infected) it self every where including saves..

Might i suggest a "new tool".
'
Though i used the "repack from XML", it will throw an error that ***.package is not found (since it was deleted), but i think one can ignore it, or edit the XML-file and remove the reference to it.
I haven't installed the file i repacked, so no idea if it will work or not, but when i opened the new sims3pack with CUSTARD, the damn counter was gone.

Ah, don't get me wrong.

I had no problems with CUSTARD.

My first attempt was "self-cleaning" by unpacking (using s3su), deleting the viral counter .package, editing the .XML, then repacking (using s3su).

Not sure where I went wrong; the resulting file can't even be re-unpacked using s3su...

Afterwards, I used CUSTARD, and the cleaning was successful.

(Side note: I've successfully used s3su before to edit other sims3pack files, and never experienced this corruption problem before. So that's why I didn't immediately realize that the Launcher crash was caused by a corrupt sims3pack).

The doll was not intentional, and i don't think the counter was either.

As a side note: .package files can attach them self to sims3packs (especially on sims) and many times it don't have to do with "bad file/s, i've encountered that several times, hence why many dispice sims3packs.