Happens to me too, the same error, but when alt tabbing on the song selection window. Then on return to osu!, black screen for some secs, and crash.
Happens only on some songs, on other songs, something weird happens :
My default playfield (Skin), is a blank image, so when going on song without a background, the background is just black.
But when I alt tab out of the song selection screen on some songs, and going on a song without a background, the background is replaced by the picture of the song that was selected when I alt tabbed.
I'll try to see if it does on some songs in particular or if it's totally random.
Dunno if it can help, but well, better than nothing.
And sorry for the video, can't really record atm, maybe i'll do it later if it can be useful.
Well, I tested it a bit, and I noticed that alt-tabbing a lot makes a significant fps drop (120fps ~ 60fps after something like 10 alt-tab). Dunno if it's related, but still pretty weird.
Oh, and doing it enough times (20-30 maybe) makes osu! crash with this error :
Such errorSystem.InvalidOperationException: Begin must be called successfully before a Draw can be called.
at Microsoft.Xna.Framework.Graphics.SpriteBatch.InternalDraw(Texture2D texture, Vector4& destination, Boolean scaleDestination, Nullable`1& sourceRectangle, Color color, Single rotation, Vector2& origin, SpriteEffects effects, Single depth)
at Microsoft.Xna.Framework.Graphics.SpriteBatch.Draw(Texture2D texture, Vector2 position, Nullable`1 sourceRectangle, Color color, Single rotation, Vector2 origin, Vector2 scale, SpriteEffects effects, Single layerDepth)
at #Lm.#Mm.#Ms()
at #Lm.#sp.#Ms()
at #fj.#kj.#Ms()
at #rb.#xb.#Ms()
at #1h.#0h.#Ms()
at #rb.#xb.#7s()
at #rb.#xb.#it(Object , EventArgs )
at #rb.#Bb.#Dt()
at #rb.#Rb.#Sv(Object , EventArgs )
at System.Windows.Forms.Application.ThreadContext.System.Windows.Forms.UnsafeNativeMethods.IMsoComponent.FDoIdle(Int32 grfidlef)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at #rb.#Rb.#ot()
at #rb.#xb.#ot()
at #1h.#np.#Iwb(String , Boolean )