So when using the new 64-bit client on any modern computer/laptop, you can run into some of LotRO's classic graphics issues. Specifically, crashing on tabbing out, not being able to activate Directx 11, or encountering strange colours (usually in a blue spectrum).
These are all easily fixable, and below I'll post the relevant solutions/links to make sure you get the best out of the game. The 64-bit client is definitely worth it.
If you'd like to switch to the 64-bit client, you can do so in the launcher settings
Game Error / (crashing when tabbing)
While adjusting video settings, or multi-tasking by alt-tabbing to other applications, LotRO crashes, generating "Game Error " and/or "Game Error " and then the "lotroclient has stopped working" error.
No DirectX 10/11 option
Strange Spectrum of Colours (usually blue)
LOTRO's 64-bit client is not recognised by your graphics card drivers, so your CPU/laptop is continuing to use the Intel integrated graphics chip, resulting in poor performance and other problems.
Thanks to Hurin on the forums you has solved most of these. Any more issues post here and we can work through them!