happens to me too.
Just to let you know, instead of dropping medikit/ammo box etc on the ground, just put it in your hands and you will be able to take anything inside without put it on the ground.

Still going on with 30.113860, only with handgun animation.

Happens to me, I've already created a report

[0001060: Stuck in animation while sitting down. (F3)]

Bug was from 113734 server version.

The crash came from a different version between client and host.
Nothing to see about the M4 firing.

confirmed.

Thank you, I feel retarded about it now, my bad.
Please close this report.

Are you sure you didn't pressed the walk key (shift) twice ?
Try to press it again twice to unlock the walking command. (can be use with most keys of the game)

Happened to me too a few times, I didn't check but I think that it can come from a different version between client and host. (772 or 734)