Usually you'd expect your Client and Server environments to be in sync but there are specific issues when it isn't the case and this can lead to unexpected conversions when inserting text. We suffer from this issue as our server environment is in "American" whereas our clients are usually in "British".
It doesn't cause massive issues but occasionally, especially with Oracle e-Business Suite, this can catch us out (typically it's due to it trying to look up a UK-English translation of something in an API call that doesn't exist).
Here's a quick guide to update your client-side environment.
First of all open "Registry Editor" (type "regedit" under Start Menu > Run) and search for NLS_LANG. you'll see something like;
I've highlighted the NLS_LANG entry, as you can see in the image it's currently set to;
From here it's just a quick matter of double-clicking the entry and updating it.
NOTE: It's always worth doing a "Find Again" to get the next instance of NLS_LANG just in case you have multiple clients installed.